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THE GREAT VIENNA TELESCOPE 



\STRONOMY 



The Sun and His 

Family 



/ 

By JULIA Mac NAIR WRIGHT 

Author of " Nature Readers, Seaside and Wayside," 
" Botany," etc. 



ILLUSTRATED 



' As heaven's high twins, whereof in Tyrian blue 
The one revolveth in his course immense, 
Might love his brother of the damask hue 
For like and difference: 

1 For different pathways evermore decreed 
To intersect, but not to interfere : 
For common goal, two aspects and one speed, 
One centre, and one year." 



Philadelphia 

The Penn Publishing Company 

1898 



{55 



Copyright 1898 by The Penn Publishing Company 



•; : „3b. 



* 0f 







NO 



\ 



TWO C iCEIVEO. 



CONTENTS 



CHAP. ^GE 

I The Fairy Story of the Skies 5 

II The Home of the Sun Family 17 

III The Parent Sun 26 

IV The Sun's Eldest Child 36 

V Son Uranus 47 

VI Saturn, the Eing Wearer 57 

VII The Increase of the Sun Family 67 

VIII The Sun's Small Children 79 

IX Bed Mars 89 

X Green Earth 100 

XI The Early Days of the Earth 110 

XII The Earth's Daughter 120 

XIII More About the Moon 128 

XIV White Venus 138 

XV The Sun's Youngest Child 148 

XVI Eclipses and What They Tell 157 

XVII The Story of the Tides 167 

XVIII The Far-off Stars 176 

XIX Meteors and Shooting Stars 186 

XX The Vagrants of the Sky 196 



ASTRONOMY 

CHAPTER I 

THE FAIRY STORY OF THE SKIES 
"This majestical roof, fretted with golden fire." 

The sun has set and a deep, rosy color lies along 
the western horizon. In the clear blue above this 
pink band a large star, with a soft, steady white 
light, shines out, the first of the evening host. Half- 
way up the eastern sky the moon has climbed, silver 
bright. The moonlight falls in a broad, glittering, 
bronze track across the waters. 

In this line of light the rowboats and small sail- 
boats rock at anchor, each little fishing vessel with 
one steadying sail set; the trading schooners lie 
waiting for a favorable wind ; they look like silver 
ships with silver sails. Such is the illusion of the 
moonlight. 

We dwellers in the Occident and the North are 

5 



6 astronomy 

told that the true glory of night is never revealed to 
us ; it is in the Orient and over the desert that the 
splendor of the heavens is fully shown, and there 
the starry hosts won their first worshipers, almost 
compelling man to adoration of the created and the 
seen, because of such surpassing glory. 

Nowhere in our Western w^orld can the heavens be 
more beautiful, more beguiling to our thoughts than 
near the sea, when the great, blue, scintillating dome 
bends over and mirrors itself in the wrinkling or 
foam-flecked waters, reproducing the starry lights a 
thousand fold. Of such a scene, Flammarion, the 
Romance Astronomer, writes : " The sky is studded 
with brilliant stars, the air is calm and slumberous, 
the silence of profound peace covers the earth, and 
in the smooth mirror of the w r aters the heavenly 
bodies are reflected, opening a new w T orld before our 
eyes. Thought floats between two immensities ; the 
infinite sky, the w r ater, peopled also with stars." 

In such beauty, when the uproar of the day has 
died almost to silence, fancy revels in the long, bright, 
wonderful, seemingly endless story of the starry hosts. 
We look at the white moon and consider how she 
draws the tides. The sea is brimming like a cup full 
to the overflow. It seems as if the w r aters rounded 
up like a bowl turned upside-down; they seem to 
rise toward the moon, and long to reach her. We 



Gbe Jfairg Stors of tbe Skies 7 

almost see the silver chains by which she draws the 
floods to herself. But those silver chains no eye 
can see. Why does that serene planet covet these 
oceans? It is that the earth is the mother of the 
moon. Long ago the moon sprung out from the 
earth, as a child springs away from its mother's 
arms, and since then earth's truant moon-child has 
never returned. Yet twice in each tw r enty-four hours 
a great longing for her mother seizes the moon, and 
she draws with all her might to bring that mother 
to herself. As for six hours she pulls steadily with 
those silver chains known as '"" attraction " in our 
mortal speech, the waters feel the drawing and heap 
up on the side of the earth toward the moon. If the 
moon stood still and continued to . pull the seas, 
they might overflow all the astonished lands.; but 
always at the end of six hours, the moon becomes 
discouraged and relaxes her pull ; she has moved so 
far along in her journey around the world that she 
is pulling other waves. 

In this fairy story of the skies, however, we are 
but telling half facts, and half facts are dangerous ; 
really the moon is pulling or" attracting the earth all 
the twenty-four hours, and the waters are as con- 
stantly rising to meet her. In her trip around the 
world she exerts her power at its maximum on dif- 
ferent places, and those are the places which are just 



8 Setronomg 

beneath her; as she passes on her way the place of 
greatest attraction changes. 

The moon attracts or draws the land as well as 
the water, but we do not notice this so much, so we 
speak freely of her drawing the tides and very 
seldom about her drawing the land. There is high 
tide twice each day on each side of the earth ; the 
low tides are the half-way stations. 

It is well to think high thoughts ; it leads us to 
living higher lives. Let us study for a while the 
real story of the skies, not the fairy story, but the 
story that is true. Yet the real story is very like 
the fairy story. The moon was once a part of the 
earth. As the earth went whirling round and 
round, that force which is called tangential, or 
centre-flying force, caused a portion of the whirling 
ball to fly away. That flying part was the moon. 
As tangential force flung it off, after a while another 
force set to work and kept it from flying on, out of 
sight forever. This second force is called attraction. 
Every large body or mass will exert this force more 
or less strongly upon other bodies. The attraction 
of the earth holds the moon from moving farther 
away, and the attraction of the moon creates tides 
upon the earth. 

Let us say that the case of the moon and the 
earth is like the case of a cup and ball. The ball 



Gbe JfaitE Stors of tbe Skies 9 

goes a certain distance, and the string hinders it 
from going farther; the string represents attractive 
force. If the cup is whirled by the handle, that 
whirling acts upon the ball, and one can keep it at 
the end of the tense string, whirling about the cup 
from which it was flung. There are many points 
where the cup and ball fail as an example of the 
case of the earth and the moon, but let these do for 
the present. Did the moon then break off in a great 
lump, leaving a deep hole where it tumbled out of 
the earth ? Was that deep hole the hollow where 
now the ocean runs ? We are getting back to fairy- 
tale talk ; there was no lump, no hole. When the 
moon flew from the earth the earth was not a solid, 
not even a liquid ; it was a great globe of gas, 
thinner and hotter than anything we can imagine. 

Suppose that when that flying-off happened some 
being from afar, some angel or sprite, had been 
looking on, w T ould that one have felt wild surprise at 
the evolutions of that moon-piece ? Not at all. That 
onlooker would have already seen many such vio- 
lent dividings of matter ; this forming of the moon 
was far along in the series. What, then, was the 
first one ? Who can tell ? Of that the wisest knows 
nothing. All that any one knows is something, and 
that a very little, of what happened in one little cor- 
ner of the universe, in what is called our solar system. 



10 Bstronomg 

We look up into the sky ; since we began to think 
of this story of the skies the sunset color has faded 
from the west, the dome is darker blue and all 
aflame with myriad lights. A broad band of light 
lies like a ribbon across the heavens. We call it the 
Milky Way. It is a part of the heavens where the 
stars seem crowded together, as if they even touched 
each other, and in so seeming they mingle into one 
path of effulgence. In very truth they are far, far 
apart. It is only distance that makes them seem 
near ; all heavenly bodies are far apart. This must 
be so because of tangential and attractive force. If 
they were too near the pull of attraction would 
cause the smaller body to fall into the larger ; the 
strong pull would bring the smaller body out of its 
orbit. It must be just near enough to be held ; not 
so near as to be drawn from its proper place. There 
must be a balance of tangential and attractive 
force. 

Each heavenly body has its path in space, its 
appointed track, called its orbit. Sustained in space, 
these innumerable worlds travel their eternal ways 
and never interfere ; each moves responsive to some 
sublime, unchanging, perfect law. To be able to 
discover, and in some degree interpret and appreciate 
such law, is one of the great privileges of the human 
mind. 



Gbe Jfatrg 5tot£ ot tbe Sfefes 11 

The broad band called, from its white appearance, 
the Milky Way is one of many nebulae with which 
space is set. The white appearance is caused by the 
immense number and distance of the stellar systems 
which form these clouds of splendor. We speak of 
stellar systems, and we speak of our solar system: 
here is a distinction without a difference, for every 
sun is a star, and every system is a stellar system. 
This vast nebulae which crosses the sky like a 
white ribbon, is made up of many of such stellar 
systems as ours, but most of them in all probability 
far larger than our own. Each particle of that ap- 
parently closely sown star-dust is a sun, and the 
systems that surround these suns are so distant that 
we cannot discern them even as star-dust. Let us try 
to fix our minds on the thought that this nebulae of 
the Milky Way is only one of myriads of nebulae, 
each lying like an isle of light in the seas of space, 
or anchored on the bosom of that vast dark ocean, 
as the ships are at anchor here in the harbor. This 
Milky Way we understand is far from the largest of 
these isles of light, yet for a ray to flash from one 
extreme of its greater axis to the other would require 
seventeen thousand years ; yet light flashes seventy 
thousand leagues a second ! Truly, now, we are 
thinking great thoughts, thoughts which take away 
our breath and dazzle our eyes, and leave us feeling 



12 BetronomE 

very insignificant. Yet, it is something to be able to 
reach such conceptions as these. 

For convenience in study astronomers, from the 
earliest ages, have grouped together certain stars 
which come within one field of observation. Star- 
gazers have seen that between certain stars they 
could trace some rude outline of some known thing, 
as, for instance, a chair, a dipper, a crown. These 
stars were set together then as the constellation of the 
Dipper, Crown, Orion, etc., etc. We must, however, 
remember that the stars in a constellation may have 
no real relationship, no nearness except that which 
we have made for them, in fancy, and on our astro- 
nomical maps. 

While a constellation is a thing arbitrary, and 
arranged for human convenience in study, a system 
is made up of bodies which really belong together, 
and have interdependence and mutual relationships. 
Thus our earth is part of the solar system, the centre 
of which is the sun. All the planets in this system 
have sprung from the sun, are held in their places 
by his attraction, are reached by his beams, and have 
mutual dependence and relations. The laws which 
govern this system are harmonious and invariable; 
they have been discovered, and their nature is such 
that with some degree of certainty we can assume 
that they are not limited to the solar system, but 



Zhc ffairg Stovy of tbe Skies 13 

extend through all space, and govern the most dis- 
tant nebula?. And how distant and how numerous 
these are we cannot conceive. Also we have equal 
reason to believe that ,: star stuff " is the same in all 
nebulas and all systems. 

When we think back from distant to near, 
what shall we seek for and what shall we find in 
this little system of ours — the solar system — about 
which we know that little something, — aggregate 
of the researches, discoveries, deep-thinkings of the 
wise of many ages? What is the life-story of the 
solar system ? How are worlds born, and how do 
they grow ? What is the story of the sun and his 
family ? 

When we begin with the sun where shall we go 
to find him ? We must needs go to the Milky Way 
to find the sun and his family. Here we trace 
thought-ways over which many minds have passed 
before. Xo doubt the heavenly bodies, distant, 
mysterious, splendid, were among the first objects 
which drew the studious thoughts of men. The 
early years of the race were not the age of the bar- 
barians, but of the thinkers. The thinking may 
have had its child-like simplicity at first, but it 
arrived at great results. Doubtless the first careful 
observers of the skies were the shepherds, who 
watched the flocks by night; the mariners, whose 



14 astronomy 

little craft hugged the shores ; those desert traders, 
the men of the caravans, who, resting in the heat of 
the noon-day, traveled on in the quiet coolness of the 
night. The rising and setting of the sun was matter 
of common observation to all classes, and it did not 
take long to learn that there was not a new sun every 
clay, but that the same orb disappeared in the west, 
and rose again in the east. The farmers, no doubt, 
early interested themselves in the varied positions 
of the sun in the sky during the different periods of 
the year, marking the changes of the seasons. The 
mid-summer sun is high overhead at noon, but the 
mid-winter sun hangs low in the sky even at noon. 
Thus it was seen that the sun had a yearly as well 
as a daily movement. 

The men whose business gave them opportunity 
to watch the skies at night, while the day laborers 
slept, slowly discovered other motions of the heavenly 
bodies ; those especial stars, or those groups of stars 
which seemed to have some interdependence, also 
slowly journeyed toward a setting ; and as the year 
passed on the positions of these constellations in the 
sky varied. 

Year by year, as the long-lived, patient watchers 
of the skies recorded their observations, they saw 
that the sun had in his yearly journey one invariable 
path, moving through the domain of certain constel- 



Gbe ffait£ Stors of tbe Sfefes 15 

lations, and these they named the zodiac, and divided 
into twelve signs, or stations, for the year. Then, as 
the heavens must be supposed to dominate the 
earth, by these zodiacal signs they governed their 
affairs and employments. 

Sir Robert Ball suggests that observations of the 
journey of the moon among the stars, the discovery of 
its times and phases were first understood, and the 
knowledge of the sun's yearly motion came later. 
But this was not all ; these thoughtful observers of 
the early time in their close searching of the skies 
during wakeful night hours, had discovered that 
there were five bright bodies, unlike all the others in 
the blue dome ; while other stars held their places, or 
moved only as the whole concave seemed slowfy to 
wheel about, these five bright lights were wanderers 
among the stars. They named them planets or rovers. 

Slowly, for many ages observations were made and 
theories were formed. Once, even the wisest had 
thought the earth a great ocean-surrounded plain, 
somehow upheld, around which the heavens re- 
volved ; the earth great, the heavenly bodies, its 
attendants, smaller. In the second century a. d. 
Ptolemy, the astronomer, produced a work which for 
fourteen hundred years ruled the thinking of men in 
all that concerned astronomy. Ptolemy had found 
arguments to prove that the earth is a sphere ; he saw 



16 BstronomE 

it poised in space ; he held that it was there fixed, 
and that all the starry hosts revolved about it. One 
great thinker said to him, " Do you not see that if it 
should be that this earth-ball revolved, then the ap- 
parent moving of the whole heavens could be ac- 
counted for ?" 

The astronomer assented, but rejected the possi- 
bility that the earth did move ; he held that it was 
absolutely fixed in its place, neither rotated nor pur- 
sued an orbit. The sun, moon, and planets moved, 
he said, and they moved in great circles, the proof 
of which was, that only circular motion could be 
perfect, and as the heavenly bodies could be im- 
perfect in nothing, therefore each must pursue a 
circular path through space about the earth. Such 
was the early astronomical system of those who had 
arrived at no real conception of the laws and re- 
lationships of the sun and his family. 



CHAPTER II 

THE HOME OF THE SUN FAMILY 

" Heaven's ebony vault 
Studded with stars unutterably bright." 

Day is the time to study botany, geology, and 
many other sciences ; solemn, restful night invites 
us to look upon the star-set skies, and review what 
the wise have said and noted after sunset. 

We say " up " in the sky, and "down" here on earth, 
to begin with. Is that right ? Perhaps some one on a 
far-off star says, " up " of here, and u down " of there. 
There is no up or down in space, in matter of fact. 
That is a form of expression, continued for conveni- 
ence from the times when people believed that the 
earth was a vast plain, surrounded with water, and 
that the sky was over it, as a bowl may be turned 
upside down over a plate. 

What we call " sky " is merely the limit of our 
vision in space. We speak of the horizon line where 
land and sky seem to meet ; that is merely as far as 
we can see. Your eyes are better than mine, and 
are able to see farther off than mine. We both have 
a limit, determined by the rotundity of the earth. 
2 17 



18 Bstroncmg 

Some certain place is twenty-five miles from us ; we 
cannot see it, because on the rounding of the earth 
it falls below our vision. 

" I have seen mountains fifty miles off," says some 
one. True : they were so high that they came into 
view. You did not see the ground-line of those 
mountains. 

Why are the skies blue ? we ask as we look 
above us. They are not blue. About our earth 
is an elastic envelope, from one hundred and 
twenty to tw o hundred miles thick ; w^e call it the 
atmosphere. The gas portions moving w r e know as 
air ; air violently driven we call wdnd, moving at 
different rates of speed. Thus while we cannot see 
our atmosphere except for the blueness, we can feel 
it. The blueness of w 7 hat we call sky is caused by 
the depth of atmosphere into which we gaze. All 
clouds are within our atmosphere ; they are caused 
by the condensation of water which has risen in in- 
visible vapor from the surface of our globe. As we 
watch these lovely clouds we say to ourselves, " If I 
had eagle's wings and flew above our atmosphere, 
would I find it all golden light ?" Then reason replies, 
" If you had such wings you could go no higher than 
the eagle. When you rose above a certain distance 
the air would become so thin, or rare, that you could 
not breathe. You would suffocate, as a fish does when 



Cbe Dome of tbe Sun ffamil^ 19 

taken out of water— unless you first froze to death. " 
Yes, we are dealing with fact, not fairy lore. Why 
should we freeze to death when rising nearer the sun ? 

The little gain in nearness to the sun w r ould not 
make up to us for the loss of heat; reflected from the 
earth. The glass roof of a greenhouse admits sun heat 
but does not readily allow it to pass out. It is " a trap 
to catch a sunbeam." The atmosphere is our glass 
roof, the heat poured by the sun on the earth is held 
here by the atmosphere. Close to the earth's surface 
the atmosphere is most dense, and retains most heat. 
As we rise higher the atmosphere is thinner and less 
heat is retained. Of course, if we could get half-wa}^ 
to the sun let us say, we would find heat enough to 
scorch us. All mountain tops are cold, often snow- 
covered the year round, even in the tropics. 

Let us fancy, however, that we could rise far be- 
yond our atmosphere. The deep blue would slowly 
darken — it would not change to golden light, but to 
intense blackness. Darkness reigns in stellar space. 
Our atmosphere is full of atoms of dust which seize 
and reflect the light poured from the sun, or from any 
light-reflecting object. By means of this reflection 
and refraction light is rendered visible. If we wan- 
dered into starry spaces we should be lost in awful 
darkness, unless we found something to serve, as 
does our air and the dust it contains. 



■i 



20 astronomy 

How many stars should we find in space ? No 
one can tell. Those seen by the naked eye, although 
we call them countless, are only about five thou- 
sand, clearly visible. The telescope brings more into 
view. 

Each of those stars is a sun, perhaps much larger, 
hotter, brighter, than our sun. Each of these suns 
is the centre of a system, each turning on its axis, 
and each journeying along some fixed path, carrying 
with it its planets, held by its attraction. Those 
planets we cannot see. 

Beyond the stars which we see, with their systems 
wheeling about them, may be millions more of sun- 
stars, in a multitude and distance of which it startles 
the mind to think. It almost overwhelms us even 
to fancy so many rushing along, worlds on worlds, 
suns on " suns in golden splendor burning." 

The machinery of the universe is perfect. Each 
sun, each system, moves in a fixed ordered path ; 
these paths may intersect, but never interfere. God 
makes no mistakes, and His machinery never breaks 
down. We may learn something about these distant 
sun-stars by the use of the telescope and spectroscope ; 
what we learn shows us that the same laws govern 
distant space that govern our system. 

Where is our system in space ? we ask as we 
look abroad. We find it hard to believe that we are 



Zbc 1bome of tbe Sun ffamflE 21 

a part of the Milky Way. Although that looks so far 
off, above us, and entirely out of our range, it is 
really our part of space, and in it our sun and his 
family find their home. 

How many queries these skies suggest. In regard 
to the more distant stars, we may learn that they are 
single, double, or even triple ; that they are variable ; 
that they are of different colors : purple, red, blue, 
white, yellow, green. They can be weighed, but not 
measured. They are weighed by wonderful instru- 
ments, and by means of difficult calculations which 
we need not discuss in these simple studies. When 
all is told, we find that we know almost nothing 
about the far off sun-stars and their satellites. 

Into our system come wanderers from afar, vagrants 
of the skies, we call them comets. They may have 
traveled through those black and silent spaces, and 
visited suns and systems which the most powerful 
telescopes have never brought into view. They may 
have been drawn by the attraction of those other 
suns for a time, and then, breaking away, have 
come to us. They come and go, and tell us nothing. 

Meanwhile our sun holds in good order his well- 
governed family about him, and does not allow them 
to stray off in the reckless company of the comets. 
For this well-disciplined family, the sun generously 
pours out light and heat. He gives not only the 



22 Bettonomg 

light and heat which they need and use, but so much 
more, that, as a well-known astronomer says, " The sips 
that a flying swallow takes from a river is as far from 
exhausting the water in the river, as are the planets 
from using all the light that streams from the sun." 
We use the words " stars," " planets ;" can we use 
them interchangeably? Do they mean the same kind 
of body? Not at all ; a star and a planet differ widely. 
Our sun is a star; if all stars are made of the same 
" stuff " or matter as our sun, then the material that 
makes planets is the same as that of which stars 
are formed, for planets are made out of the material 
of their central suns. The planet is distinguished 
from a star by its disc and its motion also ; planets 
reflect light, but do not pour forth light as the sun- 
stars. Several of the planets were, when first seen, 
thought to be stars, until their motion through space 
betrayed them to be individuals of our own solar 
system. The most distant of our sister planets is 
immensely nearer to us than the nearest star, and 
thus even the farthest off of our planets reveals to 
the telescope a disc, which the nearest star is too 
distant to show through our most powerful telescopes. 
Could we bring those far-off stars into as close view 
as our sun, we should, no doubt, find them possessed 
of all the characteristics of the sun, light-givers of 
unutterable, unendurable splendor, immense, slowly 



Che 1bome of tbe Sun 3famil£ 23 

rotating, their envelopes rent and convulsed as is his, 
by leaping, struggling fires. 

All this that the telescope reveals to us was un- 
known to those ancients, who, before history began 
to be recorded, gathered knowledge of the hosts of 
heaven simply as their unaided eyes could carry on 
observations. One does not then wonder that these 
first astronomers knew so little, but that they knew 
so much. It was much to detect those " sky wan- 
derers,'* the five early known planets, and to name 
them and understand something of their motions. 

The true theory of the universe was unknown 
until about the time of Columbus. Almost simul- 
taneously the heavens and the earth revealed their 
secrets. The heavens unfolded to wrapt student 
minds the marvels of the solar system. The earth 
showed a new Avorld, cradled on the waters near the 
gates of the sunset. 

Copernicus is the next great light in astronomy in 
order of time after Ptolemy. Ptolemy took a great 
forward step in knowledge when he assured himself 
that the earth was a globe, but he left it fixed in 
space, the centre of a system, and the greatest body 
of that system. Copernicus established the great 
facts that the earth rotated on its axis, and that the 
seeming daily motions of the heavens was really due 
to the revolution of the earth itself. After this he 



24 Bstronom^ 

assigned to the earth its true position in the uni- 
verse : it was one of the planets revolving about the 
sun, one of the smallest of these planets. The sun 
was the shining centre of our system, and about him 
wheeled six planets, the five known to the ancients, 
Mercury, Venus, Mars, Jupiter, Saturn, and the 
Earth. 

All this Copernicus demonstrated before a tele- 
scope was invented ; that marvelous lens that should 
bring the distant near and introduce men to the 
wonders of the heavens was not yet invented. 
Simple dials and instruments for measuring the 
length of the shadow cast at noonday by the sun 
had been used in the calculations of the ancients. 
Three years after Copernicus died, Tycho Brahe was 
born, and on him the mantle of Copernicus seemed 
to have fallen. The King of Denmark built for 
Tycho Brahe an observatory, and there for twenty 
years this last of the astronomers without telescopes, 
studied the motions of the stars. 

Galileo, born in Pisa, in 1642, was an astronomer 
with a happier destiny. When he was thirty-five 
years old the first astronomical telescope was con- 
structed. In that square, gray Torre Galileo on the 
low hill above Florence, Galileo, the father of modern 
astronomy, wandered into new worlds until then 
" beyond our ken." 



(Tbe 1bome of tbe Sun 3famit£ 25 

The telescope is an instrument fashioned on the 
principle of the human eye. When the pupil of the 
eye is dilated to its utmost, then the most light is 
admitted, and the image cast on the retina has the 
greatest brilliancy. Such objects as distant stars 
may not be bright enough to excite vision. The 
telescope on its great lens catches beams which are 
too large to enter the human eye-pupil, and then 
concentrates these great rays into a strong, vivid, 
smaller ray, which excites the sensation of vision on 
the retina. 

The larger the object glass in a telescope the more 
light it receives, and the greater is its power of re- 
vealing the hidden and bringing the distant near. 

In looking at a telescope we are full of admiration 
for the scientific ingenuity which fashioned it, and 
with wonder that any valuable astronomical work 
was done without instruments, which now seem so 
indispensable. It is the telescope which has explored 
for us the sun, his home, the number and manners 
of his family. 



CHAPTER III 



THE PARENT SUN 



" The sun, the centre and the sire of light, 
The keystone of the world-built arch of heaven." 

" How can we know anything about the sun," one 
demands, "when it is too bright to be looked at?" 
The moon, by hiding the sun, helps us to study it. 
" How can the small moon hide the great sun ? 
How can we study that which is hidden?" Look 
toward a house and hold, say, an oak leaf before 
your eyes. The oak leaf hides the house. It is not 
so much the relative bigness as the nearness of the 
one object to the e) T es which enables it to hide an- 
other. The moon is so much nearer to the earth 
than the sun is that when, in its journey around 
the earth, the moon comes between the earth and 
the sun, the sun is hidden. This is called an 
eclipse. 

There are three kinds of eclipses. When the 
moon comes between us and the sun so that the 
moon shadow crosses only one portion of the sun, 
that is a partial eclipse. When the shadow covers 
all the face of the sun, it is a total eclipse. When 
26 



?Tbe ipatent Sun 27 

a ring of sunlight is seen all around the moon- 
shadow, that is called an annular eclipse. 

During a total eclipse of the sun the light begins 
to grow dim and birds and beasts seem uneasy. 
Looking through the smoked glass one may see a 
dark shadow, like a small part of a circle, creeping 
upon the glowing face of the sun. This black 
shadow enlarges, moving along the sun's face until 
that face is entirely covered by a circular shadow as 
large as the sun. Soon this begins to move beyond 
the sun's disc, and the part that had first been 
shadowed shows a margin of light. This increases 
until the last edge of the shadow slides away and 
the sun is as bright as ever. 

A total eclipse of the sun affords the best oppor- 
tunity for sun study. The sun being shadowed by 
the moon, all about the shadow we have a circle of 
brilliant, waving, flame-like light; this is called the 
corona. Beyond the corona leap up great spires 
and shafts of light, known as faculse or torches. 
These are not different from the corona, but are the 
highest parts of it. 

An eclipse lasts but a few minutes, and is not 
visible from all parts of the earth at the same time. 
When an eclipse is to take place astronomers hasten 
to the cities or other points from which it can best 
be seen. Various instruments are prepared, and 



28 BstronomE 

when the eclipse occurs the observers are busy, some 
taking photographs, some studying the phenomena 
through telescopes, others using the spectroscope. 
When the eclipse is over the observers describe, 
compare, and discuss the various observations which 
they have made. 

Around the edge of the sun are always to be seen 
prominences of brilliant burning matter, in great 
tumult. The light of the sun at ordinary times ren- 
ders these torches nearly invisible, but during the 
obscurity of an eclipse they come out clearly. They 
are called heaps, jets, plumes; some leap up two 
hundred thousand miles from the sun's surface. 
These strange objects are masses of burning gas. 

We have seen a sudden jet of flame start from 
some lump of burning coal, and with a puffing, hiss- 
ing sound reach beyond the bars of the grate. 
From the burning central mass of the sun, vast jets 
of gas start up in flaming splendor of various colors. 
The surface of the sun is always in this commotion 
of burning plumes and peaks. 

We have seen a prism held in a ray of sunlight ; 
it divides the ray into its various colors ; red, 
orange, yellow, green, blue, violet rays are cast upon 
a surface. An instrument called a spectroscope di- 
vides the light of the blazing sun plumes into their 
various colors. Different substances give forth vari- 



Gbe parent Sun 29 

ous colors of flame. We have noticed red, blue, 
yellow, green flames in the grate. If you throw in 
salt or soda you will change the color of the flames. 
There are various colored flames in the grate be- 
cause of various substances in the fuel. Each sub- 
stance burns with its own proper color, and this 
color does not vary. 

When the spectroscope divides the colors of the 
burning gas-spikes about the sun, and reflects upon 
the screen the various colors for the observer, then 
we certainly know what material is there burning in 
the spike, for its color-tale is told, and is reliable. 

The spectroscope can also tell the color-tale of the 
far-off stars. We burn the various substances which 
compose our globe, and from the flames of their 
gases we receive certain colors. We find these same 
colors, divided by the spectroscope, from the burn- 
ing sun spires, and we say that without a doubt the 
sun is composed of the same elements that compose 
our earth — for example, gold, iron, carbon, oxygen, 
and so on, in the form of solids or gases. 

The spectroscope and other instruments have 
been so arranged that the sun can be observed and 
studied at any time, but a total eclipse affords the 
finest opportunity for sun study. 

Not only has the sun its wonderful flame wreath, 
shooting up into cones and banners of fire ; it has 



30 Battonomg 

strange spots upon its surface. These spots vary as 
do the prominences. What the spots are has not 
been fully determined. Many astronomers conclude 
that they are rents or holes in the sun surface, 
through which the burning inner gas leaps out into 
the flames of the corona. It was by observation of 
these spots that the great fact of the turning of the 
sun upon its axis was discovered. 

Now what facts do we know about the sun? 

I. The sun is found to be the centre of our sys- 
tem. 

II. It is, to the system, the source of light and 
heat. 

III. Its attraction holds the planets of the system 
in their orbits. 

IV. The sun is a globe, more than a million times 
larger than our earth. 

V. The distance of the sun from our earth is over 
ninety-two millions of miles, a number greater than 
we can realize or imagine. 

VI. The sun-spots have shown us that the sun is 
rolling over upon its axis. Our earth turns over 
once in twenty-four hours ; the sun makes its revo- 
lution in twenty-five da} s. 

VII. We have learned that while we say in gen- 
eral that the earth moves and the sun stands still, 
the sun really moves through space, journeying 



Gbe parent Sun 31 

along an immense fixed orbit, carrying with it our 
entire solar system, with no variation of the relative 
distances of the planets. 

VIII. Another grand fact learned is, that the sun 
and all the planets of our system are made of the 
same substances. 

IX. The light of the sun is white light ; its appar- 
ent yellow or golden tint is due to our atmosphere. 
From the white light we learn that the sun is not 
mere gas, nor is it a solid ; it has probably a fluid 
crust, within which is gas ; the sun is doubtless sur- 
rounded by an atmosphere of gas through which 
blaze up the flames of the corona and facul^e ; these 
last vary so much that a spire may double its 
volume three or four times within the space of an 
hour. 

The immense energy of the sun, causing these 
ceaseless changes, is a vast source of heat. The 
whole substance of the sun is in the highest possible 
state of heat. Xo fires of which we have any knowl- 
edge offer comparison to sun-combustion. It is true, 
however, that some good astronomers think that the 
sun-centre is cooled. 

In respect to the other portions of the starry 
heavens, the sun is merely one of myriads of fixed 
stars. Xo doubt millions of these stars are greater 
and more brilliant than even our wonderful sun. 



32 Betrcmomg 

The laws that govern our system, the processes of the 
birth and growth of worlds here, doubtless hold 
good in all the other systems. From the one we 
know something of the many. " The sun is big 
enough for us at all events," we say in dog-days ; 
" what would August be with a bigger sun?" Yes, 
we can say to our sun if his size is disparaged — 

" Be pale afar, since still to me you shine !" 

The worship of the sun w r as one of the earliest forms 
of idolatry. The Assyrians found among plants the oak 
tree, as a symbol of their sun-god, and among beasts 
the bull. To make the bull a more fit emblem of the 
sun-god they added to its images eagle's wings and a 
human head, thus uniting strength, swiftness, and wis- 
dom, they had an image of the god who had hung the 
sun for his symbol in the heavens. A Persian fire- 
worshiper, whose chief divinity is the sun, once said 
to an Englishman : " The reason you northern people 
do not worship the sun is, because 3^011 have never 
really seen him. If he rose on you with the glory that 
he shows to us Persians, you would worship him." 

Milton, in many passages of his poems, sung the 
matchless splendor of the sun ; and as w r e cannot fail 
to realize, the advance of science, and our increas- 
ing knowledge of the " great luminary," serve to 
emphasize and give significance to such passages as — 



Zbc parent Sun 33 

" Thou sun, of this great world both eye and soul '"' 

"At whose sight all the stars 
Hide their diminished heads." 

Far as our earth lies from the splendid source of its 
heat, we should not be warmed by its rays were it 
not for our atmosphere which spreads all about us, 
softening and diffusing, and returning the solar 
beams. Yet, if out of its course our earth strayed 
a little nearer to the sun, it would shrivel in its heat, 
as did the servants of Nebuchadnezzar, who ap- 
proached to the seven-times heated furnace to throw 
in the three Hebrew heroes. 

When w T e speak of size we are at a loss for com- 
parisons. For every acre on the surface of the earth 
there are ten thousand acres of sun-surface. " If the 
earth were represented by a mustard seed, then on 
the same scale the sun should be represented by a 
cocoanut," says one writer. If we could collect 
and set to work sun heat, w r e should have no need 
for coal, wood, gas, or electricity for heating. One 
single square foot of sun surface pours forth heat 
sufficient to produce continuous steam for a twenty 
thousand horse-power engine. The heat is not lack- 
ing ; all that is lacking is ability to grasp and apply 
it. If, instead of the system which has sprung from 
his mass and is governed by his attraction, our sun 
3 



34 BetroncmB 

had set around him in a " fiery ring " or coronal two 

thousand million globes such as our earth-home, he 
could provide warmth and light for them all. How 
childish was then that old idea that that splendid 
star of day came into being merely to nourish and 
equip this little world. 

As far as we know the sun is the great sample 
spendthrift in existence. He sets his world-children 
an example of unsurpassable wasteful extravagance. 
He seems to squander his riches merely for the sake 
of lavish display. Off into space go light and heat, 
practically untaxed by the orbs of our system, so 
small is the portion received by them, in compari- 
son with the amount distributed. What becomes 
of all that magnificent expenditure of solar radiation 
science has never discovered. It is, however, among 
the possibilities that science will yet so enlarge its 
powers that it may go into space after that apparently 
idly lavished largess, and find it not thrown away, 
but performing marvels of useful work. 

When the greatest of multi-millionaires runs a 
course of boundless lavishment people say : " How 
will even millions stand that strain ?" So one asks 
of the sun, " How is he going to keep up his ex- 
penditures?" As for fresh supplies of heat-giving 
material, Professor Langley states that the entire 
earth flung into the sun, as a stoker tumbles fuel 



tlbe Iparent Sun 



35 



into the fires under a great boiler, would not main- 
tain the sun's lavishment for a single minute. All 
this has been going on for ages that cannot be num- 
bered. What, then, keeps the heat up ? Helmholtz 
discovered an answer for this question. The sun 
keeps up his own heat — by shrinking ! If the sun 
were solid, by this time he would be cold and inert. 
If the sun were liquid he would have cooled to a 
tepid state and have no more heat than he needed 
at home ; but the sun is largely gaseous, and being 
gaseous he daily contracts, and that contraction 
squeezes heat out of the sun, as pressure squeezes 
water out of a wet sponge. As long as this gaseous 
state continues and shrinkage goes on, our solar sys- 
tem will be well supplied with heat ; and so vast is 
the volume of the sun that for incalculable ages this 
outpour may proceed without sensible diminution 
of light or heat. 



CHAPTER IV 

THE SUN'S ELDEST CHILD 

"Worlds on worlds are rolling ever 
From creation to decaj T , 
Like the bubbles on a river, 
Sparkling, bursting, borne away." 

Let us go back to the beginning of things, to the 
time when no worlds swung in space, far back to the 
time when there was nothing at all — even when 
there was no time ! That is quite impossible ; the 
mind cannot go back so far. Then let us go back to 
when there was nothing in our system ; we will be 
satisfied with the less if we are denied the much. 
As far back as we can think, there was very much 
in our system. What we want to know T is how the 
first planet began its course— the story of the sun's 
eldest child. Let us look far out beyond the low- 
hung moon and the nearer stars until we see among 
the constellations a thin, bright cloud, like a little, 
crumpled, tissue veil. Search the sky carefully to 
find more such faint luminous cloudlets. 

Yes; one over there, one high up in mid-sky. 
Those are called nebulae or clouds. To our eyes, 
36 



Zbe Sun's ]£U>est CbilD 37 

or to a telescope of low power, the nebulae seem 
to be mere patches of dim haze. By means of a 
powerful telescope some of them will be found to 
be star clusters, so far off that their light unites, and 
we cannot see space between them. There are other 
nebulae which the most powerful glasses cannot 
resolve into stars ; they remain burning clouds. 
The spectroscope is set to write their story, and that 
shows that they are composed of gas, burning at a 
high degree of heat and tenuity, to which nothing 
known here can afford a comparison. 

Some of the nebulae seem to be turning on an 
axis. No one has yet settled the origin of the heat 
or the beginning of the spin of sun-spheres. It is 
not worth while to give here the various explanations 
suggested. Let us take it as proved that these 
nebulae, composed of burning gas, show us the state 
of our system before the first planet was formed. 

The sun is now more than a million times larger 
than our earth, and has probably a fluid crust. Let 
us go back to the time when the sun was many mil- 
lion times larger than now, hotter in proportion, and 
had no fluid crust. It was simply a vast globe of 
burning gas, revolving rapidly on its axis. 

Let us use an illustration. If one whirls a wet 
mop, when it reaches a great speed the water begins 
to fly off. If you dip a wooden paddle into molasses, 



38 Bstronoms 

boiled to the candy point, and gathering up the 
thick molasses on the stick, begin to whirl it, as } T ou 
whirl very fast, little lumps of the molasses begin 
to fly off. A velocity so great might be reached 
by machinery that the little lumps that flew off 
would themselves continue whirling about for a 
time. 

This illustrates what we wish to explain, that this 
vast sun-sphere of glowing gas, spinning at a tre- 
mendous rate, went at last so fast that it could not 
hold together, and some of it was thrown off. 

This portion did not go in a lump, or globe-like 
mass. It was thrown off around the equator, or 
great circle about the centre of the globe, the cir- 
cumference where the diameter is greatest. The 
portion set free was a vast, luminous, gaseous 
ring. 

Did you ever say that ) T ou were running so fast 
that you could not stop ? It was so with this ring ; 
it had gained so much velocity from the parent 
globe that it kept spinning on, in the same direction 
as the ball from which it had been freed. 

Children are usually like their parents in appear- 
ance and manners. This first child of the sun was 
like the sun in substance and motion. 

A ring cannot hold together as well as a ball ; it is 
too large in extent for its thickness at any one point. 




CHANEY'S PLANETARIUM 



Gbe Sun's Eldest CbiR) 39 

This ring thrown off from the sun broke up, and, by 
attraction of its parts, collected into a ball. 

Stop a minute : let us settle matters as we go on. 
Why did not the parts tumble back into the sun by 
sun-attraction ? Because, when first thrown off, the 
ring went so far from the sun that the attraction of 
the parts for each other was greater than the attrac- 
tion of the sun over them, so they fell together. 
Thus in our system one planet was formed. 

Why, when the ring broke, did not the several 
parts go on and on, each in its own direction? How 
could the parts collect themselves ? We must con- 
sider first, that the ring, when it broke up, still had 
its parts remaining in the line and curve of the ring, 
and continuing the previous motion or journey. 
Lack of cohesion or attraction in the ring had per- 
mitted its division ; the attraction of the original 
body prevented further departure from its centre. 
Any ring so dividing will have some parts nearer 
together than others ; these will come together. A 
larger mass being formed by these unions, w T ill 
exert more attraction and so collect more frag- 
ments. 

The ring state is shown, as will be seen hereafter 
in Saturn ; the coming together of broken rings 
into several satellites can be noted in Jupiter and 
other planets ; the collection of all fragments into 



40 Bstronoms 

one satellite by the case of the earth and the 
moon. 

The velocity of the sun-ball caused it to give the first 
planet such a tremendous fling when it was cast 
off that it went very far into space, was sent, in fact, 
to the outpost of our system. This new planet was 
like a grown-up lad, who becoming restless sets off 
on a journey to see the world, and to satisfy his eager 
curiosity goes as fast and as far as he can, while 
his father supplies his expenses and gives him his 
directions. 

Our sun did not lose influence over his traveler in 
space. When the planet had gone to a certain dis- 
tance, it could get no farther away ; the attraction of 
the sun held it by invisible chains. Having reached 
its limit, it revolved on its axis, and traveled about 
the sun in a vast, far-off orbit, nearly circular, but 
slightly elongated, or, as it is called, elliptical. This 
is the shape of the orbit of all planets. 

Wh) T did not the sun-globe fling off a planet 
sooner ? The reason was that as the sun-bail whirled, 
it cooled ; cooling causes contraction or shrinkage, 
while contraction causes a swifter whirling. This 
process was needed before the point of throwing off 
a ring could be reached. 

What was the name of this first planet, and where 
is it ? It has been named Neptune, and is the out- 



Gbe Sun'e JElbeet CbtlD 41 

most planet in our system. It dwells on our bound- 
ary line in space ; it is our sentinel planet. Comets 
which come flaming in, pass on their way this vast 
fiery ball, which proclaims to them that they have 
entered the dominions of the sun. 

Why is Neptune fiery ? One would think it might 
have cooled by this time; it is countless ages since it 
formed. It has grown cooler in the uncounted ages 
since it found its place, but it is so vast and was cast 
off with such velocity, at such an intense degree of 
heat, that it is still a ball of burning gas. Neptune 
is thirty times farther from the sun than the earth 
is, so far off that from its surface the sun would ap- 
pear as a great star. Owing to this great distance 
from the source of light for this system, the stars 
would be visible from Neptune clay and night, if the 
condition of its atmosphere rendered seeing anything 
possible. 

Neptune is one hundred times larger than our 
earth. Its orbit is so vast that it takes one hundred 
and sixty-five years to traverse it. Our earth com- 
pletes her orbit in three hundred and sixty-five days. 

No telescope yet made has been able to discover 
features on the disc of Neptune ; a very powerful in- 
strument is needed to discover that it has a disc at all, 
great fiery thing though it is ! Neptune has thrown 
off a ring of matter which has collapsed into a ball, 



42 BsttonomB 

and this ball is Neptune's little moon, which travels 
around Neptune as our moon travels around our 
earth. The moon of Neptune moves at such mar- 
velous speed that it makes its circuit in six days. 

The planet Neptune was discovered in 1846. 
Before this date it had been occasionally seen 
through telescopes, but had been mistaken for a star 
until it had been searched for as a planet. A star 
does not change its station, and has no disc. In 
searching for a wanted planet, Neptune, then without 
a name and supposed to be a star, was discovered to 
have motion and a disc. 

Why was a planet searched for ? 

Until then Uranus was supposed to be the out- 
most planet of our system. We know that while 
the sun by its attraction holds the planets in their 
orbits, planets influence each other by their attrac- 
tion. It was found that Uranus was disturbed, at 
certain points in its orbit, as if swayed by the attrac- 
tive force of some body other than the sun. Astrono- 
mers decided that there must be some great exterior 
planet and a search for it was rewarded in 1846 by 
the discovery of Neptune. This search for and 
finding of Neptune was one of the great triumphs of 
astronomy. 

Why did they think the new planet was beyond 
Uranus ? 



Gbe Sun's Bluest <Xbtlfc 43 

A planet large enough to exert such attraction, 
would have been visible, if within the circle of 
Uranus. Neptune is very large, the third in size 
among the planets. 

This discovery of the planet Neptune is a story of 
wonderful interest. It was no matter of accident; it 
was an affair of scientific research. Invariable laws 
ruling the planets had been discovered : for every 
perturbation or variation there must be a certain 
sufficient reason. A young Cambridge scholar, 
named Adams, having made careful studies of 
Uranus, saw that the presence of a planet exterior 
in the system would account for the various eccen- 
tricities of Uranus. He finally went to the Royal 
Observatory at Greenwich, and showed the Astrono- 
mer Royal, in charge there, the place in the skies 
where search should be made to find another child 
of the sun. 

In the meantime Arago, a French astronomer, had 
called the attention of another famous French star- 
gazer, Le Verrier, to the singular behavior of Uranus, 
and Le Verrier also had made calculations, assuring 
himself that there must be an exterior planet, and 
indicating where it should be found. His calculations 
placed the desired planet only one degree from the 
place claimed for it by Adams. Here, then, was a 
very wonderful case ; two astronomers pointed out 



44 BstronomB 

the existence and almost the exact position of a 
planet that had never been seen ! 

Now was the time to begin a careful search. The 
method of search was this — an accurate chart was 
made of the part of the sky indicated as the residence 
of the distant unseen planet. Such charts of various 
parts of the heavens are now in the hands of many 
astronomers, but at that time no English astronomer 
had one. The making of such a chart involved much 
time and great labor, for the especial part of the sky 
had to be mapped out, all the visible stars in it care- 
fully set down in their places, then all the stars 
brought to view by the telescope in that field must 
be added with the greatest accuracy, and then every 
night the sky thus mapped must be studied, and 
the stars in the sky compared with the stars on the 
chart to know if one of them was a rover. This 
chart work fell to Professor Challis. He marked out 
the region where the new planet was claimed to be, 
observed all the numerous bodies in that portion of 
sky and measured their distances. He used the 
great Northumberland Telescope, at Cambridge 
Observatory, England. He resolved after making 
his chart to go over it carefully, comparing star with 
star, and then a second and third time, and note if 
any vagrant had left his marked place. In truth 
Professor Challis did see Neptune and mark him as 



Cbe Sun'e lElfceet Cbtto 45 

a star more than once, and a continuance of the 
observations would have assured him that this was 
the sun-child sought for. 

In the meantime from France, Le Verrier had set 
the astronomers in Berlin and Paris at work planet 
hunting in a field of sky which he marked out. 
Several years previous one of the Berlin observers 
had made a star chart, and at the very time Le Verrier 
wrote to Berlin, asking for search for his planet, the 
chart of the particular part of the heavens which he 
indicated had just been engraved, but was not yet 
published. The day was September 23d ; that night 
the sky was dazzlingly clear ; the chart was laid out ; 
Dr. Galle turned his telescope to the part of the blue 
vault indicated by Le Terrier's letter. One star after 
another was reviewed, identified, and found in its 
exact place on the chart. Finally Dr. Galle called 
out a clear, bright star of the eighth magnitude. " It 
is not on the chart," said the assistants. All was 
excitement, but astronomers need be careful, and 
perhaps there had been a mistake, and a star had 
been overlooked in making the chart. The men of 
the Berlin Observatory could scarcely wait for an- 
other night ; it came brilliantly clear. Again the 
review began, star by star, and here again was this 
clear, glowing star of the eighth magnitude. But 
where ? It had left its place ; it had moved along 



46 astronomy 

an orbit ; it had pursued the very path Le Verrier 
had foretold. They measured it; it had the exact 
diameter Le Verrier had asserted that it must have. 
This glowing jewel on the front of night had disc and 
motion, and shone with reflected, not self-outpoured, 
splendor. The child of the sun had been found. 
Here was the glorious reward of patient labor. For 
months Le Verrier and Adams, each unknown to the 
other, had fixed their minds on calculations and 
formulae ; they had reached human hands through 
space to grasp a planet on its tremendous journey ; 
science had made its triumph ; the planet was found. 



CHAPTER V 

SON URANUS 

" Look how the floor of heaven 
Is thick inlaid with patines of bright gold." 

" I wish," we say when gazing toward a pale 
silvery patch among the far-off stars, " that I could 
see nebulae plainer." We would doubtless find 
them very beautiful. Few objects surpass them 
when seen through the telescope. In addition, 
they lie at star beginnings. Let us know something 
more about them. Their state was once ours. 
They are named from the constellations within 
which they are seen. They may really be millions 
of miles away from these constellations, but, seen 
from the earth, they appear within their limits, and 
we so consider them for convenience. Some are 
called globe nebulae and some ring nebulae, from 
the shapes they take. 

In the constellation of Taurus, or the Bull, is the 
nebula of the Crab ; it is shaped like a great crab 
with extended claws. Sobieski's Crown is another 
strangely shaped nebula. In the constellation of 
Argo there is a nebula shaped exactly like a regula- 

47 



48 Ustronom^ 

tion comet, with a burning head and a long, fiery 
tail. In the constellation of the Dog is a spiral 
nebula, a succession of spirals revolving upon each 
other in a blazing vortex. 

Near the southern pole of the sky there are few 
stars visible, but there lie the Magellanic Clouds, 
two of the largest and most magnificent nebulae, 
looking like a great storm of snow, where every 
flake is a patch of fire. The spiral nebula in the 
constellation of the Virgin is one of the most splen- 
did objects upon which a telescope can be brought 
to bear. It is uplifting and enlarging to the mind to 
know of these glories in the sky, even if they lie be- 
yond our sight. 

The Milky Way itself is an enormous nebula in 
which are myriads of completed systems, and myr- 
iads more nebulae which are yet whirling clouds of 
gas. The shape of the Milky Way is that of a wide 
ribbon, deeply notched at one end. What keeps 
these nebulae from flying to atoms like dust and 
scattering about space ? 

Attraction. The force of attraction of part for 
part holds the parts from going beyond a certain 
limit, and by degrees draws them closer, until the 
vast revolving mass becomes a whirling ball. 
When Neptune was first formed no doubt it swiftly 
removed by tangential force to its present place, and 



Son THranua 49 

then attractive force held it there. So of the other 
great planets. Their first place was their constant 
place. By such processes our system was formed. 

What was the second planet of our system ? 

Uranus. Uranus was thrown off from the sun 
by the same process as Neptune, and next after Nep- 
tune. Uranus can only be seen through a strong 
telescope. It is sixty or seventy times larger than 
the earth, but is composed of so much lighter ma- 
terial that it is but fifteen times heavier. The dis- 
tance of this planet from the sun is so great that it 
requires eighty-four years to complete its orbit, 

Uranus has cast off a ring, or rings, of matter 
which broke into satellites, or moons. Four of 
these moons are known and named. The one 
nearest Uranus makes its circuit in two and one-half 
days, and the outmost one in thirteen days. A very 
strange fact about them is that they move from 
east to west, and not from west to east, as do all 
other known moons. Why this is no one has yet 
discovered. Sir Robert Ball says that in the early 
history of this planet there must have been local in- 
fluences at work different from those which affected 
other bodies of our system. 

At first more than four moons were assigned to 
Uranus, but some of these have been shown to be 
enormously distant stars, which chanced to enter 
4 



50 Hstronomfi 

into telescopic view near the planet. We ask our- 
selves, " Why do the moons of Neptune and Uranus 
finish their circuit so much sooner than our moon 
does, when our planet is so much smaller?" It is 
because the orbit of our moon is really greater than 
theirs, as it is so far from our earth. The moons of 
Uranus and Neptune are very near their planets. Our 
moon w r as once much nearer our earth than now, but 
has slowly retreated. The nearness of the Uranian 
and Neptunian moons to these planets suggests that 
they may have been cast off at a comparatively 
recent period. Moons are at first near to their 
parent planet, and by tidal force drift away. On 
the other hand, the great planets remove at once to 
their orbits, and do not linger by the sun. Perhaps 
this difference is due to the greater vigor or force of 
the output. 

When was Uranus found, and who found it? On 
the night of March 13th, 1781, an astronomer named 
William Herschel was studying the sky through a 
telescope that he had made for himself. On that night 
he found this planet. Herschel was an organist and 
music teacher, but so great a lover of astronomy that 
he devoted to that pursuit all his spare time and 
means. For eight years he had been carefully ob- 
serving the sky, aided by his sister Caroline, who 
shared his passion for star-study. Herschel w r otild 



Sen Ulramis 51 

observe the stars through his telescope and detail 
what he saw to Caroline, who sat by his side to write 
out his observations. The succeeding clay, while 
Herschel was busy with his music teaching, his 
sister worked out all the needed astronomical calcu- 
lations. 

Herschel had resolved to examine the sky with 
care, and to map out all stars of a certain brightness. 
He had directed his attention to the constellation of 
Gemini, or the Twins, when he saw a star very dif- 
ferent from the others. It had a disc — a very tiny 
but true disc. 

The eyes of Herschel were remarkably keen, and 
his mental perceptions very quick. Other astrono- 
mers had seen this body and had called it a star ; it 
had changed its place and they had considered it 
another star, not the same body in motion. 

Night after night Herschel marked carefully this 
wonder. At first he fancied it might be a comet. 
But no; he soon saw that it was no comet, but a 
body with a disc and moving in an orbit — a planet — 
a new planet, lying far outside of Saturn, which had 
until then been called the frontier orb of the solar 
system. 

This discovery made Herschel a famous astrono- 
mer. King George III became his friend, built an 
observatory for him, and gave him a pension that 



52 Betronomg 

he and his sister might live near Windsor and devote 
themselves entirely to astronomy. 

Herschel wished to name his new planet after 
King George, but the astronomers of the world ob- 
jected to changing the ancient order of naming, and 
called the new planet Uranus, from the eldest of the 
gods of fable. 

A careful study of the path of Uranus showed a 
vacillation and deviation in its motion. Uranus did 
not seem to be obeying the laws which govern our 
system — u Kepler's laws," as they are called, because 
he first clearly formulated and explained them. 
What was the trouble with Uranus ? Was this sec- 
ond son of the solar family an unruly child ? What 
was influencing him ? He seemed to be paying at- 
tention not only to his parent sun, and to his 
younger brothers grouped between him and the sun, 
but to somebody beyond him. His attention was 
often seriously distracted. This became a matter of 
serious consideration. 

In fact, Uranus was spending a part of his time 
corresponding with his elder brother, Neptune. At 
that time we, here upon earth, knew nothing about 
Neptune, but, of course, the sun understood all about 
him, and the devious ways of Uranus did not trouble 
him. 

Astronomers set themselves to explain the erratic 



Son ratanu0 53 

and absent-minded conduct of Uranus, and, as was 
narrated in speaking of Neptune, this observation 
resulted in the discovery of Neptune in his incon- 
ceivably distant home. The planet of Uranus binds 
to immortal fame the name of the music-master-as- 
tronomer, William Herschel. He was one of the im- 
mortal few whose passion for star-study has ruled 
their lives, and the gratification of it has been more 
to them than meat and drink. If Herschel had not 
been famous as an astronomer, he might have been 
widely known as a remarkable maker of telescopes. 
The problem before him was this — he needed a tele- 
scope, but his means were inadequate to the purchase 
of even the mediocre instruments of his day. With 
indomitable energy he set about making a telescope. 
He was a man of extreme accuracy in all his under- 
takings, and as the result of several years labor he 
produced a very superior telescope. The fame of 
this instrument spread abroad, and various nobles 
and crowned heads requested him to make telescopes 
for them. By the sale of these he secured means for 
carrying on his own studies. The enthusiastic pas- 
sion of Herschel for astronomy, his energy, persist- 
ency, his conquest of difficulties, all bring to mind an 
astronomer of the present day, Camille Flammarion, 
now world-famous. For him the stars are full of 
romance — so also is his scientific life full of romance. 



54 BBttonom^ 

A devotee of astronomy, not abundantly furnished 
with fortune, Flammarion, some fifteen years ago, had 
succeeded in getting together enough money to pur- 
chase a large telescope, but he had nowhere to 
mount it. The setting up of a telescope is about as 
costly as the instrument, for solidity in the founda- 
tion is required or the telescope is perverted by the 
jar. Professor Gavazzi Smyth e once said that the 
great telescope in the observatory on the Calton Hill, 
Edinburgh, in spite of its isolation on the hill, and the 
immense piles of masonry upon which the instru- 
ment was placed, responded to the jar occasioned 
by wagons and drays rolling over the pavement 
down at the foot of the hill. 

Flammarion concluded to ask his landlord to allow 
him to set up the telescope upon the roof of the 
house where he was then living. While he was con- 
sidering plans and expense he received a very extra- 
ordinary letter signed E. Meret, Bordeaux. This 
letter contained an offer of a house, land, and money 
wherewith to set up a great private observatory at 
Juvisy, a village near Paris. Now the professor had 
often had practical jokes passed upon him by foolish 
folk who cannot understand why one should study 
the stars. He concluded this letter was another 
such joke, and did not reply to it. A second and a 
third of like tenor came. The third read in this 



Bon TUtamis 

way : " I am more than seventy ; I am beginning to 
lose my eyesight. But others live in the light and 
know how to diffuse it. I repeat to you that I pos- 
sess at Juvisy a small estate, where formerly I 
dabbled with astronomy. That land I do not wish 
to sell — I wish to present it to you. Its secular 
shades will prove to you an oasis of blest repose. 
Only answer me by one word, l yes.' You will then 
go and see it. If you do not like it, then you will 
sell it." 

It was just at this time that Flammarioirs work, 
" Popular Astronomy," leaped into unexpected and 
unprecedented sale, and produced for him in a short 
time 820.000. Here was money for the equipment 
of his observatory, and an observatory was the desire 
of his heart. Flammarion was now convinced that 
the letter from Bordeaux was sent in good faith. 
Instead of writing " yes " he went to Bordeaux and 
saw Monsieur Aleret. He found that the pretty little 
estate in Juvisy. which was now made his own. was 
called " Cour de France " or i; French Court." because 
in long-gone years the kings of France going from 
Paris to Fontainebleau used to stop there while 
their horses were changed. In this same house, 
; * Cour de France." Xapoleon I slept the last night 
before his abdication in 1814 — probably not slept, 
but remained awake, would be the fitter phrase, 



56 Betronoms 

Here at last arose on a low hill the tower of 
Camille Flammarion's observatory. Here he has 
gathered together beautiful astronomical and photo- 
graphic instruments, and here he can make himself 
happy in his own especial way, studying the heavens 
and writing about them. 

It is Flammarion's good fortune to be able to tell in 
graceful speech what he has seen and knows. 
Added to this fluent and elegant description are the 
illustrations of his subject, which photography 
enables him to make, and thus his work has done 
much to popularize astronomy. 

Since the discovery of Uranus and the consequent 
discovery of Neptune, much of the modern 
astronomy is intensely mathematical and technical, 
and it is a boon to the popular mind when a descrip- 
tive writer such as Flammarion, dowered with enthu- 
siasm and imagination, can do something to bring 
astronomy near to the general heart. 



CHAPTER VI 

SATURN, THE RING-WEARER 
1 'The planets in their stations listening stood." 

" If we were flying through star space, what would 
be the most splendid object that we should see ?" This 
is a question often asked by those watching the skies 
on clear, brilliant nights. 

We cannot possibly guess what is the crowning 
glory of stellar space, but we can easily say what 
would be the most splendid object within the solar 
system, and it is hard to conceive that anywhere in 
the heavens can be found a more glorious planet 
than the third in order of the sun's children, next in 
magnificence to the sun himself. We will assume the 
sun's superior grandeur as a fact. The most wonder- 
ful sight within our solar system is the planet Saturn. 

The five planets, Mercury, Venus, Mars, Jupiter, 
Saturn, were known to the ancients, who named 
them from their gods. They are visible to the naked 
eye, and were called, as before said, " sky-wanderers," 
because they changed their places. They were 
always understood to be different from the stars in 
their nature. 

57 



58 Bettonom^ 

All that we know of these planets is the slow 
accumulation of facts, gathered by ages of observa- 
tion. After telescopes were invented, closer study 
enabled people to have a better acquaintance with 
them. For many hundred years Saturn was con- 
sidered the least interesting of the planets. It was 
supposed to be the outmost orb in our system. 

The distance of Saturn from the sun causes its 
motion through its orbit to be much slower than 
that of the nearer planets. This vast distance from 
the source of light also causes Saturn to be less 
brilliant than the other four planets which we have 
named. 

A noted astronomer says : " To me it has always 
seemed that Saturn is one of the three most interest- 
ing celestial objects visible to observers in northern 
latitudes. The other two are the great nebula in 
Orion and the star cluster in Hercules." 

Observers in southern latitudes might add to these, 
or put in place of one of them, the constellation of 
the Southern Cross. 

The superior magnificence of Saturn cannot be 
known to the unaided eye. Seen without the tele- 
scope it is merely an orb more or less bright, accord- 
ing to its distance from us as it traverses its orbit. 

At the farthest point of his orbit Saturn is some 
thousand millions of miles from the sun. The time 



Saturn, tbe TRing&meatet 59 

required for his journey through this great path is 
over twenty-nine years. 

Although Saturn is seven hundred times larger 
than our earth, it whirls so swiftly upon its axis that 
it turns over once in ten and one-half hours, while 
our earth requires twenty-four hours for one revolu- 
tion. On Saturn the days would be but half as long 
as ours, but the seasons would be each about seven 
years long, instead of four months ! 

Saturn is the centre of a wonderful and compli- 
cated system of his own. This system occupies a 
space of four and one-half millions of miles diameter. 

Saturn's system has been built out of Saturn, as 
the solar system has been built out of the sun. 

We remember that when we speak of world build- 
ing we begin with a whirling, burning globe, which 
casts off a burning ring. The great glory of Saturn 
is that he has continued to cast off rings, and these 
have not all collapsed into moons. Some of them 
are yet visible, through the telescope, as rings. 

We must talk a little more about world building, 
in order the better to understand the wonders of 
Saturn. Each planet having been cast from the sun 
surface, receives from him its motion, and revolves 
upon its axis in the same direction as the sun turns 
upon his axis, because the sun gave the planet that 
impulse before it parted company with him. 



60 Bettonoms 

The first form of the cast-off portion being the 
ring, the orbit of a planet continues to be nearly 
circular. The plane, or level, on which it moves, 
closely coincides with that of the equator of the sun, 
because the matter was originally cast off from that 
region. The simple experiment of whirling dough 
or thick tar upon the end of a stick will show us that 
when a ring of stuff flies off, it goes from the central 
portion of the mass, and so when stuff flies off from 
the sun to make any planet, or from a planet to 
make a moon, the portion which in whirling has 
bulged is the equatorial zone, so matter goes off from 
the central, or tropical part, midway between the 
poles. Let us fancy a vast nebula of irregular form ; 
the parts attracting each other. By the law of gravi- 
tation these parts settle toward a centre, or may be 
to several centres, if parts with equally great attrac- 
tive force are found. If, in a nebula there are several 
such points of attraction, several suns would be 
formed, and consequently their several systems 
would be evolved. 

The nebula resolves itself into suns by the forces 
of attraction and gravitation. The particles come 
together toward a centre. Some consider that be- 
cause the particles rush upon the centre from dif- 
ferent sides that gives the mass the initial or first 
twirl, just as to set a top spinning we take the stem 



o 



2 

o 

m 

> 



o 
o 
% 

in 



o 




o 



o 



o 



Saturn, tbe IRfn^lDQearer 61 

between our palms and pull one palm swiftly toward 
us, and push the other swiftly from us ; this double 
motion creating a whirl which causes the top to 
spin. 

The ball being formed and set spinning, its speed 
increases as shrinkage continues, and owing to this 
speed there is a heaping up, or tidal wave of 
material at the equator. When this heaping up 
reaches a point where it can overbalance gravitation, 
or the pull toward the centre, a ring of surface-matter 
will detach itself and remain poised. This ring will 
revolve in the same plane and direction as the body 
from which it parted, because it received both motion 
and material from that body. 

When Saturn reached the point of casting off 
rings, the first ring or rings flung into space finally 
broke into moons. . Saturn is the richest in moons 
of any planet, having eight ; some of these are very 
small. 

Saturn then cast off other rings which have not 
broken up. If we stood upon Saturn and looked 
up, we would see two magnificent arches, bright* as 
the crescent moon, bending from horizon to horizon — 
a pair of great gleaming bows, revolving with terrible 
swiftness. Were it not for this swift rotation, causing 
the parts to cohere, the rings would go to pieces by 
force of gravitation. 



62 Bstronom^ 

" Wouldn't it be magnificent, if we had such 
rings!" we exclaim, rashly. It might have its dis- 
advantages ; for fifteen years at a time these rings 
must turn their dark sides to the planet which they 
span, and the regions below them would be hid in 
fearful night. Of what are Saturn's rings made ? is 
a frequent query, the question meaning in what state 
is the ring material, for it is clear that it is of the 
same matter as the planet. Saturn is not so tenuous 
as Uranus or Neptune. It seems to have contracted 
to a state a little less dense than water. If the ball 
of Saturn could be dropped into an ocean, the ball 
would float with one quarter above water. Astron- 
omers have suggested all manner of material for 
Saturn's rings, from big rocks to hydrogen gas. The 
spectroscope having investigated sun material, in- 
forms us of the material of which by consequence 
Saturn is made, but we do not know the degree of 
density of the rings. There is abundant room for 
more knowledge ! 

The surface of Saturn is probably a foggy envelope 
around a very hot interior. The rings are no doubt 
composed of the same gases, further solidified by 
cooling and contracting. The rings rotate in ten and 
a half hours. We have spoken of two rings ; there are 
really three, perhaps four. The two outer rings are 
divided by a dark line, which probably represents 



Saturn, tbe IRtn^HXHearet 63 

intervening space. The inner ring is so hazy that it 
is called " the crape ring." 

Now we can see Saturn with the vision of the 
mind. It is a great bright globe, whirling over and 
over, in a bright triple ring, as a ball in a hoop. Out- 
side the great rings are eight moons, spinning over 
and traveling about Saturn, while Saturn travels 
millions of miles around the sun, carrying all this 
gorgeous company with him ! This third son of the 
family has set up his own household. Let us think 
of Saturn's rings as great shining shoals of meteors 
or tiny moons, held together, whirling over, sweeping 
with Saturn through space. 

The great interest which attaches to the planet 
Saturn is comparatively modern, because his mar- 
velous system was not discovered until the telescope 
was brought to bear upon it. Neither was all this 
complicated object at once understood. The astrono- 
mer Galileo was the enchanter, and his little reflect- 
ing telescope of thirty diameters magnifying power 
was the potent wand which revealed the real Saturn 
to a wondering world. One can scarcely imagine the 
immense joy of Galileo, when turning his glass upon 
the sun he saw hitherto undreamed of spots on that 
splendid orb ; when the moon revealed to him moun- 
tains on her silvery surface ; when Jupiter displayed 
his satellites, and Venus showed a crescent like a new 



64 Batronomg 

moon! Then, full of joyful excitement, the lonely 
watcher on the little gray " torre Galileo " turned his 
telescope toward Saturn. Other astronomers with 
telescopes had already seen, as he had, the wonders 
in Sun, Moon, Venus, Jupiter ; a discovery remained 
for the good Galileo. What was this ? Saturn ap- 
peared not one body, but three — three bodies in line, 
always touching, always retaining the same relative 
places ; a great central body, and a smaller body on 
the west, and one on the east. Sight so strange had 
never before met human eyes, and Galileo dared not 
speak of what he saw, until by further study he 
co aid better comprehend the marvel. Of all men 
the astronomer must be the most patient and per- 
sistent. Week after week for two years Galileo 
watched this triple Saturn — and saw the two outer 
and smaller bodies slowly dwindle away ! He had 
during these two years asserted that Saturn was a 
triple body, now it swam in space a single body, like 
Jupiter, and he was compelled to admit it; his 
enemies and envious friends gave a howl of derision. 
When one looks at a photograph taken from a por- 
trait painted of Galileo during his latter years, one 
seems to see in the many lines the care, sorrow, and 
mortification heaped up by this contumely and doubt; 
while in the eyes the light of his final triumph burns 
steadfastly. He wrote : " I do not know what to say 



Saturn, tbe IRfn^Wearer 65 

in a case so surprising, so unlooked-for, so novel. 
Are those lesser stars consumed after the manner of 
solar spots? The unexpected nature of the event 
has greatly confounded me. Am I mistaken ?" 

Still the anxious astronomer watched the planet — 
and back came the lesser orbs to view ! More power- 
ful telescopes were then constructed, and not Gali- 
leo, but all the objectors, began a careful study. 
Presently they saw not two globes, one on each side 
of Saturn, but two shining crescents, as if the golden 
globe of Saturn had two vast crescent handles. 
After seven or eight years these crescents disap- 
peared, to return again and go through the same 
changes as before. 

Fifty years of observation were needed before the 
real nature of these appearances was settled. In 
1655 Huyghens, using a powerful lens, discovered 
the shadow of a great ring cast upon the surface of 
Saturn. What had been seen then were portions of 
a mighty ring, which portions assumed the shape 
of orbs, or crescents, or arms, according to the angle 
at which they were observed. 

Huyghens announced that Saturn was rotating on 
its axis and surrounded by a vast ring, also rotating, 
and so thin that when the edge was turned earth- 
ward it became invisible. It was nearly four years 
before Huyghens completed the observations and 
5 



66 astronomy 

calculations which explained the Saturnian system. 
He then announced, " Saturn is girt with a ring, 
tenuous, flat, distinct from its surface, rotating, and 
inclined to the ecliptic." Thus we see that at first 
the ring of Saturn was supposed to be single. 

Ten years passed before Cessini, another Italian 
astronomer, discovered that the ring of Saturn was 
not single, but double, was, in fact, two rings sepa- 
rated by a space, represented to the observer by a 
dark line. Later it was seen that the system of 
Saturn included three rings. In 1850 Professor 
Bond, of Cambridge, discovered a third ring, called 
" the crape ring," from its filmy texture. This dis- 
covery has led to the suspicion that the rings of 
Saturn, in their rotation, may be suffering change, 
and may be dividing themselves. A positive proof 
of the divisions between the rings would be the ob- 
servation of a star in or through the intervening 
space. Only a large star would thus be visible, and 
so far none has been detected in passing. The out- 
line of Saturn itself has been discovered through the 
intervening space between the first and second rings. 

Majestic, in the distant skies, Saturn sweeps along 
its immense orbit, carrying the triple ring and four 
attendant moons, not the largest but the most 
splendid and complicated among the dependencies 
of the sun. 



CHAPTER VII 

THE INCREASE OF THE SUN FAMILY 

" Night comes, world jewelled . . . 
The stars rush forth in myriads, as to wage 
War with the lines of darkness." 

It is idle to discuss time in system building. No 
mind could estimate the endless procession of seons 
during which world after world, system after system, 
wheeled into order. Was all space once flaming, 
tumultuous, w r orld building material ? Did countless 
centres of gravity assert themselves, drawing material 
together until the infinite numbers of nebula? were 
formed, and then, these dividing again by attraction 
of gravitation, and rolling and tumbling on, tor- 
nadoes of fire, system building came to be, so that in 
our nebula, the Milky Way, unnumbered systems 
shone, and other tumultuous centres were yet clouds 
of intense fire ? Even in this one nebula, this one 
system of that world building, time is left out of 
account. 

When, after the building of Saturn, the sun again 
had thrown off a ring of material, and that had 
come together into a sphere, it w r as by much the 

67 



68 Batronomg 

largest of the planets. This sphere, known to us 
as Jupiter, is the greatest of the sun family. It is 
between 1,200 and 1,500 times as large as our earth.* 
Its orbit is some 479,000.000 of miles from the sun, 
and therefore it receives much less light than our 
earth or Venus. Nevertheless, owing to its enor- 
mous size, it often shines more brightly than Venus, 
and seems truly the chief of the hosts of night. 
From this splendor of appearance the ancients gave 
it the name of the king of their gods. 

If to Saturn you added all the other planets, you 
would not have a globe so large as Jupiter. The 
shape of Jupiter is more flattened than that of our 
earth. If you take an orange between your palms, 
the stem end in one palm, the blossom end in the 
other, and press your hands gently toward each 
other, you will enlarge the circumference about the 
centre or equator of the orange and produce a shape 
like that of Jupiter. 

The orbit of Jupiter is more elliptical, or egg- 
shaped, than that of the earth. This orbit is 482,- 
000,000 of miles in extent, and the planet traverses 
it in twelve years, less fifty days. One rotation of 
Jupiter on its axis occupies nearly ten hours. Thus 

*Ball says 1,200 times larger ; Flammarion 1,500 times 
larger ; Buritt ( " Atlas of Astronomy " ) 1,300 times larger ; 
Planets can be more accurately weighed than measured. 



Gbe Uncteaee of tbe Sun ffamilg 69 

the day of Jupiter is less than half as long as ours, 
and each of his seasons is three years in duration. 
As far as we can judge, while we speak of seasons 
upon Jupiter, there would be really almost no change 
of temperature, neither summer nor winter, only 
perpetual spring. 

Then dwellers on Jupiter would have neither snow, 
ice. nor torrid summer heat ; endless spring might be 
wearisome ! They would, however, encounter greater 
disadvantages than that. Jupiter, from its vast size, 
has retained a large part of its original heat, the heat 
of its particles when they divided from the sun. 
The surface of Jupiter has not cooled to solidity. 
How nearly solid it may be we cannot tell. Walk- 
ing on Jupiter might be like walking upon the hot 
ashes lying on the sides of Vesuvius, shortly after 
an eruption — ashes which slip away and allow the 
feet to sink into the soft lava. Or, all the surface 
may be still boiling and bubbling as lava just poured 
from the crater. It may be even thinner than that, 
mere boiling mud and slime. 

Another disadvantage inhabitants would encounter 
upon Jupiter would be the terrible storms. Jupiter 
is the most stormy planet known. The fiercest hur- 
ricanes, whirlwinds, cyclones on earth are gentle as 
compared to the tempests which ravage Jupiter. 
The surface of Jupiter and its atmosphere are con- 



70 Bstronom^ 

stantly convulsed with tornadoes. On the whole, we 
conclude that there are no inhabitants upon Jupiter, 
although there are those who hold that life is pos- 
sible upon all the planets. If Jupiter is so cloudy 
and stormy all the time, how can anything be 
learned about him, we inquire. The answer to this 
question may be unexpected ; w r e learn much of his 
life-story by the observation of his satellites. Jupi- 
ter has cast off rings of matter which have contracted 
into five moons. These moons are of nearly equal 
size, and through a telescope they look like five small 
stars. We discover their true nature by finding that 
they are not fixed, as are the stars, but are ever 
roaming about a common centre, and that centre is 
Jupiter. They travel with him along his enormous 
journey through the skies. 

The nearest of these satellites to the planet en- 
compasses him in two days ; the most distant in 
seventeen days. We see, in addition to a perpetual 
spring, Jupiter has the advantage of constant moon- 
lit nights. 

Now let us consider how these little moons have 
answered an important question in regard to Jupi- 
ter. Being so large and so bright a body, the ques- 
tion arose, " Does Jupiter receive all its light from 
the sun, as do the other planets, or is it itself a light 
giver?" When we see a moon of Jupiter going be- 



Gbe Uncrease oi tbe Sun ffamflE 71 

tween the planet and the sun, we find that the great 
planet is shadowed, because the moon cuts off the 
sunlight from a portion of the surface of Jupiter. 
This proves that the great orb is not a light-giver, 
but a light-reflector, and receives its light from the 
sun. 

The moons of Jupiter give us another proof of 
this fact. When Jupiter rolls between one of his 
moons and the sun, the moon is lost to sight in dark- 
ness, because Jupiter cuts off from it the sunlight, 
and has no light of his own to cast upon it. 

One of the questions which arises when we observe 
Jupiter is, " Why does Jupiter have such fierce 
storms?" Storms on this earth are occasioned by 
sun-heat. The sun's heat evaporates and raises 
moisture from the earth's surface, which moisture 
condenses into clouds and returns to the earth in 
heavy rains or light showers and dews. Sun-heat 
also causes a vacuum here and there by making the 
air so light that it rises higher and higher. Then, 
to fill the vacuum, colder currents of air rush in, 
with greater or less velocity. These are called wind- 
storms, hurricanes, tornadoes, and so on. 

Jupiter receives too little sun-heat to account for 
its storms. They are to be attributed to its own 
heated condition. Just as the sun is always in a 
fiery storm and tumult arising from his own terrible 



72 Bstronomg 

heat, Jupiter is still hot enough in itself to create its 
own tempests. 

While Jupiter is twelve or fourteen hundred times 
greater than the earth in volume or surface, so that 
many earths like ours could be lost in its bulk and 
nearly ten of them could be set in line on its diam- 
eter, it would take but three hundred and ten earths 
to balance its weight. This is because its material 
is so expanded by heat. 

The spectroscope has shown us the elementary 
material of which that planet-source, the sun, is com- 
posed. This stuff is the same for all the planets, as 
all were cast-off portions of sun material. A cer- 
tain amount would be of equal weight in any planet, 
but the size of that amount of material would de- 
pend upon how much it was expanded by heat. 

The great volume of Jupiter affords a good field 
for telescopic study. Upon its surface a remarkable 
series of dark lines, called belts, have been found. 
These pass around Jupiter, parallel to the equator. 
Various pictures of the belts have been made. They 
all differ, because the belts are ever changing, 
in width, outline, and distance from each other. 

Jupiter has spots which change less than the belts. 
One, called the " Great Red Spot," has been visible 
for twenty years. There are also white and black 
spots on the surface. 



Gbe ffncreaee of tbe Sun ffamilg 73 

What are the belts and spots of Jupiter ? 

It is probable that the belts are layers of cloud, 
parts of which reflect the sun's light more perfectly 
than the surface of the planet does. The spots are 
probably rents, or craters, on his less than solid sur- 
face. The storms produced by the planet's highly 
heated condition convulse these cloud belts of his 
atmosphere with storms. The heavy cloud belts 
about Jupiter suggest an atmosphere loaded with 
moisture. When this moisture is high enough above 
the burning surface of the planet to escape from his 
diffused heat, it would condense into rain and snow 
and hail, as does the moisture which rises from the 
surface of our earth by the action of solar heat. Such 
condensed vapor would speedily be reconverted to 
steam when, descending, it again came within the in- 
fluence of the planet's heat. In the intense heat 
about the vast glowing surface, atmospheric excite- 
ments, such as we call cyclones, tornadoes, and whirl- 
winds, would be of constant occurrence, and of a fury 
to which the wildest storms of our earth would 
afford no comparison. 

The heat of Jupiter, great as it is, is incomparably 
less than sun-heat, and while the sun in its glowing 
state gives off light in abundance, and heat of which 
some degree reaches to the most distant planets of his 
system, Jupiter has not sufficient glow to diffuse light, 



74 Bstronoms 

nor sufficient heat to radiate heat beyond the close 
envelope of its cloud atmosphere. Jupiter does not 
illuminate his own little moons ; they, like their pro- 
genitor, enjoy the largess of their grandfather sun. 
A noted astronomer says : " Enough has been 
demonstrated to enable us to pronounce on the 
question as to whether Jupiter can be a body inhab- 
ited by living beings, as we understand the term. 
Obviously it cannot. The internal heat, and the 
fearful tempests seem to preclude the possibility of 
organic life, even were there not other arguments 
against it. It may, however, be contended, with per- 
haps some plausibility, that Jupiter has in the dis- 
tant future the prospect of a glorious career as a 
residence of organic life. The time will assuredly 
come when the internal heat must subside, when the 
clouds will gradually condense into oceans. On the 
surface then may dry land appear, and thus Jupiter 
may be rendered habitable." 

It naturally occurs to us to ask, " Why are Nep- 
tune, Uranus, Saturn, Jupiter in such a state of 
furious heat, a condition of material scarcely so con- 
densed as fluid, when they were cast off by the sun 
into space, so long before the earth, w r hich has been 
the home of organic life for myriads of centuries ?" 
The answer is found in the fact of the immense size 
of these bodies and the rapidity of their motion. 



Zhe Uncrease of tbe Sun ffamfl£ 75 

The earth, so much smaller, contracted and cooled in 
incalculably less time than these planets have de- 
manded for similar processes ; and numberless more 
ages must pass before the solid crust, the ocean 
reservoirs, the soil prepared by heat, pressure and 
disintegration, can be productive of vegetable life 
upon these elder planets. 

Our moon, so much smaller than our earth, has, in 
its briefer life period, had time to lose all its original 
fire, and become cold and silent. The condition of 
the moon hints to what state, in the long succession 
of ages, our earth may be journeying ; this case of the 
earth and the moon is an object lesson of the case of 
the planets, sent off before earth into space, but still 
in the physical condition of the earth shortly after 
its severance from the mass of the sun. As far as 
material is concerned one can see no reason why the 
life history of these planets should not correspond 
with our own. 

Modern discoveries have shown us that the ele- 
mentary substances present in the other bodies of the 
universe are those which form our globe, and we 
must deal with the questions arising about the other 
planets on the ground of similar material. We can say, 
with some assurance, that heat, motion, contraction, 
the forces which have built our earth to what it is, 
will do the same work on other planets — on Jupiter. 



76 Bstrcmoms 

When we meet other questions, as " Why, when 
Jupiter is twelve hundred times larger than our earth, 
is he only three hundred and ten times as heavy ?" 
we cannot reply, " Oh, he is made of lighter elements." 
We must say the elements are the same, but in a dif- 
ferent condition of heat and expansion. Such are 
some of the interesting directions of study suggested 
by the clear white splendor of Jupiter as the unaided 
eye marks his journey along the skies, or when 
through the telescope we detect about him his beau- 
tiful system of five small, clear, white moons. 

These moons of Jupiter have lately aroused much 
discussion. There is, in South America, at Arequipa, 
an observatory which enjoys superior advantages for 
astronomical work, on account of the great purity 
and clearness of the atmosphere on those Andean 
heights. At this Arequipa observatory certain singu- 
lar phenomena have been noticed in these little 
moons of Jupiter, phenomena known nowhere else 
in the system. 

Our moon is, as says Dr. Young, " a solid globe of 
rock." The moons of Jupiter seem to be clouds of 
fiery mist, or fog, or whirls of dust and meteoric 
stones. In fact, they seem very closely to resemble 
in matter and state of excitement the planet from 
which they sprung, and if their condition is as sug- 
gested by Arequipa observers, then they are satellites 



Gbe ITncrease of tbe Sun JfamtlE 77 

in their very earliest stages, only recently separated 
from the parent globe. As we shall more fully un- 
derstand when we come to discuss tides, there is on 
all planets tidal action, and this tidal action on the 
vast planet Jupiter, which is in such a condition of 
heat and tenuity, powerfully affects its little incoher- 
ent moons. Instead of being a globe steadily revolv- 
ing on its axis and sweeping along a regular track, 
each little moon of Jupiter twists, writhes, and dis- 
torts itself, much in the fashion of some sea-anem- 
ones. These moons change their forms from round 
to oval, and back again continuously, so that their 
real shapes are hard to determine. The first moon 
is now said to be shaped like a lemon, and to bowl 
along its track, turning end over end, and this not in 
the line of its orbital motion, but reversing it. The 
second moon is flattened, as if a lemon had been 
partly squeezed, or " like a cake of toilet soap," as 
one observer says. The third is the largest of the 
set, and is a miniature of the parent planet, orange 
shaped, but instead of revolving on its shortest axis, 
like a reasonable well-bred little moon, it whirls 
round and round as if twisting on a string, and in 
such a way as to keep the same face, or nearly the 
same, always to the planet. The fourth moon varies 
these antics by keeping an edge toward Jupiter, and 
is of a much darker complexion than the others. 



78 BBtrcmcmg 

Now, the variations of these moons from the globe 
shape are, while definite, not very pronounced, and 
seem to be clue to the incoherent state of the moon 
material, and the very powerful force of attraction 
exercised over them by the great Jupiter. 

As Mars recedes from the eastern sky, Jupiter takes 
his place and would challenge the admiration and 
close observation of every star-lover by his singular 
beauty, even if all these marvels of his size and 
system were still as unknown to us as to his ancient 
beholders. Sirius is perhaps the only rival of 
Jupiter in brightness beheld by the naked eye ; but 
Sirius is ■ so far, far off, and Jupiter is our brother 
planet, an elder and greater brother of our little 
green earth, a hundred thousand times greater than 
the earth, rivaled in size only by the parent sun. 
Jupiter is the privileged brother, the Judah of the 
sun family. 



CHAPTER VIII 

THE SUN'S SMALL CHILDREN 

' ' The skies are painted with unnumbered sparks, 
They are all fire, and every one doth shine ; 
But there's but one in all doth hold his place.' ' 

What planet comes next after Jupiter? we ask 
when we settle ourselves for another thought journey 
to the starry skies. Mars comes next. Between 
Mars and Jupiter there is a vast space, which we 
must visit before reaching Mars. We understand 
that there are no stars within the bounds of our solar 
system. Stars are suns like our sun, and each has 
its own station and system. The very nearest to us 
lies many billions of miles beyond Neptune. Be- 
tween the orbit of Neptune and the sun is the 
dominion of the sun, and inter-planetary space is 
dark as inter-stellar space. 

The distance from us of all the heavenly bodies is 
so great that to the eye, or to the telescope, the re- 
moteness of stars or planets appears equal. We need 
to measure to ascertain true distances. This far-off- 
ness has caused planets and the moons of planets to 
be mistaken for stars, until closely investigated. 

79 



80 Batronomp 

Is there then a great empty space between Mars 
and Jupiter? 

It was formerly supposed to be empty. Various 
interesting discoveries have, however, been made 
within its limits. Columbus, we know, decided that 
there must be land which might be found by travel- 
ing westward. He sailed away and discovered 
America. Astronomers having reasoned that there 
must be planets between Jupiter and Mars, traveled 
thither by telescope, and discovered new spheres. 

It had long been thought that the emptiness of so 
large a tract was not in harmony with the construc- 
tion of the rest of the solar system. 

An astronomer named Bode found that a remark- 
able law governed the relative distances of all known 
planets. The space between Mars and Jupiter seemed 
to offer the only exception. Possibly then this might 
not be empty space, but contained planets that agreed 
with the general rule. 

" If there is any planet between Mars and Jupiter," 
the astronomers said, " it must be very small, for 
being so comparatively near, a large body would 
have appeared to the unaided eyes. " 

About one hundred years ago, astronomers in all 
parts of the world arranged a plan of search. 

An astronomer named Piazzi, in Palermo, Sicily, 
undertook observations on a plan of his own. He 



tlbe Sun's Small Cbilfcren 81 

divided the stars into groups of fifty each, and ob- 
served and noted the places of these for four succes- 
sive nights for each group. The air of Sicily is 
peculiarly fitted for astronomical observations ; it is 
so clear and still. 

On the night of January 1, 1800, Piazzi noted 
what seemed to be a small star in the constellation 
of Taurus, or the Bull. He marked its place on 
his map, No. 13 of the group in hand. For three 
succeeding nights he marked the position of this 
star, and then compared his observations. He found 
that No. 13 had changed its place every night, and 
was prancing about like a little boy just let loose 
from school. In fact No. 13 was not a star at all, 
but the sough t-for planet between Mars and Jupiter ! 

The attention of astronomers was now directed to 
this planet. It was found to travel about the sun in 
an orbit of its own, not acting as the satellite of any 
other planet. It was named Ceres, after the goddess 
of harvests, a goddess of old supposed to inhabit 
Sicily. 

When in its orbit little Ceres passed out of sight, 
astronomers feared that they should lose it entirely, 
and not be able again to fix its place. A young 
German scholar named Gauss, here made a great 
contribution to science. He took the three places in 
which the little planet had been seen, and drew for 
6 



82 2t6trdrtom£ 

Ceres an ecliptic, or planet-track, of which the sun 
was one focus, the track passing through these three 
known points. The ellipse being mathematically 
correct ; having discovered from the three places the 
rate of travel of Ceres, Gauss could point out where- 
abouts the planet should be at any given time. 

This seems very simple when it is explained. It 
is the first time that counts in all such investigations ; 
and young Gauss acquired great fame and estima- 
tion for his work. 

Was it likely that little Ceres occupied alone so 
great a place ? All astronomers were now endeavoring 
to find similar small planets. During seven years, 
three more, Vesta, Juno, and Pallas were discovered, 
and the number was supposed to be complete. 
Forty years passed, and then, in the same field of 
space, scores of other little planets were discovered, 
one by one, by different astronomers. These were 
named, weighed, measured, and their orbits traced 
out, until by April, 1891, three hundred and forty 
had been found. There may be hundreds more, for 
the place they seem to occupy is very great. 

What are these little bodies? How can we 
account for their place and number, for the eccen- 
tricity, as it is called, of their paths ? This means 
that they are irregular in their orbits, departing very 
markedly from the circular. 



5be Sun's Small ClMlfcren 83 

Some astronomers suggested that long ago there 
might have been one great planet in this orbit, and 
that it had exploded from the violent action of its 
own gases, and its parts had been scattered into frag- 
ments. These fragments having gravitated about 
many centres of attraction, had formed the little 
planets which are called, collectively, the asteroids. 

Another suggestion was, that a great planet having 
been cast off by the sun next after Jupiter, some 
errant comet had come that way, and the planet had 
been destroyed by a collision, and not by an explo- 
sion. Further and more careful study makes it 
fairly certain that the asteroids, or little planets, were 
formed just as their greater brothers were, that had 
been cast off by the sun in a quick succession of 
small rings — a certain high fashion of fire- works ! 

The asteroids lie about eighty millions of miles 
beyond the planet Mars. They vary in size; some 
are only a few miles in diameter, others are a great 
many miles. Being so rnuch smaller than the other 
planets of our system, they must have been among the 
first to cool. They are probably even more solid than 
our earth, for our earth has a liquid or gaseous centre, 
or core. The tiny asteroids, most likely, have cooled 
and hardened entirely through. 

Upon their little spheres may be continents, 
oceans, rivers, mountains. They might be very 



84 Betronomg 

interesting objects to study. Unfortunately they are 
so small that the best telescopes cannot bring into 
view features upon the disc of any one of them. 
None of them are visible to the unaided eyes. 

Owing to their small mass they are easily drawn 
and swayed by the attraction of other bodies, which 
may cau^e the deviations and eccentricities of their 
paths. We can also reason concerning them that 
from their minute size, whatever atmosphere they 
have must be very light and thin, rare, as it is called. 
They are of great value in astronomy, as aiding 
in calculating the place, motions, distances of other 
heavenly bodies. 

If we were upon one of the little asteroids we 
could travel over its entire surface in a short time. I 
say " if,'' for there is a large " if " in the way — if there 
were any atmosphere that one could breathe ; if there 
were any water for one to drink ; if the attraction of 
gravity on so small a body were strong enough to 
keep one's feet upon the surface, and prevent one 
from tumbling off into space. 

Take an asteroid eight miles in diameter, our earth 
being about eight thousand. A million such asteroids 
would be needed to make an earth like ours, if the 
solidity were equal. If the mass is one thousand 
times less, attractive force would be less in propor- 
tion. If here we can throw a ball up twenty yards, 



Gbe 5un'0 Small CbilDren 85 

there we could throw it twenty thousand yards. If 
here we can jump up one yard, there we could go 
up one thousand. We and our ball might get off 
too far ever to be drawn back. 

Do we think that very amusing ? It might have 
terrible disadvantages. One might wish to jump 
over a house or to a tree-top, and might inadver- 
tently give such a send-off of tangential motion that 
one might never get back. Here we jump up and 
are drawn back, or we fall and are drawn down by 
the attractive force of the earth pulling us and all 
things within its reach, toward its centre. The at- 
tractive force on a little asteroid is so small that the 
tangential force exerted by a human boy might free 
him from the planet and set him loose in space ! 

So interesting is the search for these little planets, 
and so curious and attractive are the questions con- 
cerning them, that almost all astronomers give them- 
selves more or less to the search for them. " Asteroid 
hunters " is a common expression nowadays. Since 
it was finally decided that — 

"No suns had clashed, no planets burst ; 
The worlds whirl on their way ; 
The day makes beautiful the night ; 
The night makes glad the day — " 

the asteroids, as little individuals built on the same 



80 Bstronomg 

plan as their greater brothers, are of increasing at- 
tractiveness. 

Until 1892 the search after new asteroids was slow 
and laborious. The method was this : A portion of 
-the blue arch was mapped out ; all stars therein seen 
were carefully set down, and their places noted. This 
done, when such a field came again opposite the sun, 
the telescope swept it carefully, minutely examining 
every body visible in it, to see if some glittering orb 
appeared which was not noted on the chart. If such 
an interloper was found, still more careful study of 
it must be made, to be sure that it was not a variable 
star, or a star overlooked in a previous search. A 
few days, perhaps even a few hours, would settle 
these questions. Then a new query rose, if this new 
object proved to be really an asteroid, was it an 
asteroid now for the first time picked up by the tele- 
scope, or was it one of the older discoveries ? For 
there are several of the first found asteroids, which are 
what is called u adrift," that is, in their flight about 
the sun they have for a number of years escaped 
observation. 

One great effort of our present age seems to be to 
minimize labor, and so the labor of finding asteroids 
has been greatly lessened. Human ingenuity has 
again made a triumph. Asteroids are now hunted 
after with a camera ! This camera has a peculiar 



TLbc Sun's Small' Cbtldten 87 

lens, six or eight inches in diameter. The camera is 
sometimes strapped upon the tube of a telescope, for 
convenience in following star motion. 

The observer then photographs the region where 
he is searching for asteroids. Photography is not 
careless, it never overlooks a star. It is a minute 
truth-teller. Points which would escape the human 
eye gazing through a telescope are rigorously set 
down by the camera. The camera also will cover a 
much larger field of observation than the ordinary 
telescope. 

How large do these thousands of stars appear 
as seen through the tell-tale camera ? Each 
one on the negative will be a little round dot. 
And here is a fact worth noting. While the stars 
are each represented by a distinct dot a planet 
on the other hand, is not a dot. but drawn 
out into a little streak, because of the appreciable 
motion of the planet during an exposure of the 
camera of some hours. Xow the asteroid being a 
planet, and moving with velocity, prints itself on 
the camera as a little streak, and so the plate has 
been known to catch two or three of these tiny 
travelers at a single exposure. In the year 1893 
forty asteroids were discovered in this way. This 
simple and ingenious fashion of search was first em- 
ployed by an astronomer named Wolf, in Heidel- 



88 BstronomE 

berg, Germany. Professor Charlois, at Nice, used 
the same method. Four of the forty detected in 
1893 were old stra} r s, asteroids once seen, known, 
named, and then escaped. Also fourteen of these 
forty, while probably new asteroids, need further 
examination before they can be fully determined 
upon. Some of these new-found asteroids are from 
fifteen to twenty miles in diameter. 

One astronomer, writing of asteroids, says he is 
"seriously afraid that several thousands more may 
come into view, while their present number is 
already so large as to be embarrassing." Who, he 
inquires, is to spend time looking after all these 
little strangers, and making a chronicle of their 
doings? The multitudinous babes of the sun 
famil} T are then a troublesome element, though no 
sound emanates from that vast sky-nursery which 
lies between Jupiter and red Mars. 



CHAPTER IX 

RED MARS 

" There is no light in earth or heaven 
But the cold light of stars, 
And the first watch of night is given 
To the red planet Mars." 

Let us see if we can find Mars for a study ; it is a 
red star, and always shines very brilliantly, but the 
best time of all for seeing it is when it is in oppo- 
sition. 

What do w r e mean by that ? When is a planet in 
opposition ? "A planet is said to be in opposition 
when it is on the side of the earth opposite the sun. 
The earth is then between the sun and the planet ; 
the planet receives the full sunlight, and we have the 
advantage of looking away from the sun while we 
observe the planet. When Mars is in opposition it 
is nearer the earth than at any other part of its 
orbit. Mars is one of our nearest neighbors in the 
skies, and w r e know more of him than of any other 
planet, except the moon and the earth. When we 
have found three clearly red stars, how can we know 
which of them is Mars, and what are the other two? 

89 



90 2l0tronom£ 

One is Aldebaran in the constellation of Taurus ; 
one is Beltegeuze in Orion. Let us get the planeta- 
rium and set it with its face to the north. Note 
where Mars is set on the globe of the planetarium, 
and then follow with your eyes the line of Mars up to 
the sky. 

Now we have it ! It is the brightest of the three. 

For some time we will be able to watch Mars each 
evening, but there are parts of the year when Mars 
rises and sets with the sun and is lost in his light. 
If we were spirits roaming through the skies we 
should see two planets much alike in shape and 
general appearance. Perhaps at first we could not 
tell them apart. Then we might learn that one of 
them was called Earth, was twice as great in diameter 
as the other, and had but one moon. The smaller 
of the two is Mars. If there are people on the 
planet Venus, who look at us through telescopes, we 
appear to them much as Mars does to us. 

Looking at Mars we see a globe, slightly flattened 
at the poles, revolving obliquely on its axis, and 
turning over once in twenty-four hours. Its journey 
around the sun requires one year and almost eleven 
months. Thus the seasons of Mars are double the 
length of ours, while the day is of the same length 
that we have. 

Mars is but little more than half the size of our 



IRefc /Ifcars 91 

earth. Until recently is was supposed to have no 
moons. It was called " moonless Mars," " lonely 
Mars." In 1877 Mars was in opposition, and at the 
place in its orbit nearest the earth ; the opportunity 
for observing it was exceedingly fine. Professor 
Hall, of the Observatory in Washington, discovered 
two moons revolving about Mars. One is eighteen 
miles in diameter, the other twenty-two. The outer 
moon requires thirty-one days for its trip about 
Mars, but the inner moon traverses its little circle in 
seven and a half hours. This moon rises and sets 
three times each day of Mars ! The planet is not 
particularly benefited by such an active little moon, 
because it is so near that much of the time it is hid- 
den in its course. 

The behavior of the inner moon of Mars has no 
parallel in the solar system. As moons gradually 
drift away from their planets, being nearest at their 
first formation, the inner moon of Mars may be of 
comparatively recent origin, and may, in time, make 
a wider circuit. 

"What are the names of Mars' merry little 
moons?" Professor Hall named them after the two 
horses which Homer tells us drew the chariot of 
Mars, the god of war, Dismay and Rout ; in Greek, 
Deimos and Phobos. More than a hundred years 
before these moons were discovered, Dean Swift, in 



92 B0tronomE 

his " Gulliver's Travels," stated that the star-gazers 
on the Flying Island had discovered two moons for 
Mars, and that one of them traversed its orbit in ten 
hours. This was truly very close guessing. 

From Mars we learn the weight of our earth. If 
Mars had no attraction to sway him but the sun, his 
path would be forever the same. Our earth, his 
nearest neighbor, is large enough to disturb his orbit 
by attraction. Mars is pulled toward the earth. 
Astronomers take the position in which Mars would 
be if attracted only by the sun, and then take the 
place into which he is gently pulled by our earth. 
The difference between these two is all due to the 
pull of the earth. It is then necessary to calculate 
how large a mass is required to exert so much at- 
tractive force ; thus the mass or weight of our earth 
is learned. 

When Mars comes nearest the earth, features on 
its disc are clearly observed through the telescope, 
and Mars has been well studied. The poles of the 
planet are found to be capped with snow, like our 
own. Maps have been made of the surface of Mars, 
and these look curiously like a sketch map of our 
world, drawn on " Mercator's Projection." There 
are singular markings on Mars which can scarcely 
be accounted for except by the presence on the 
planet of bodies of water. 



1ReD /Hbare 93 

The presence of water is also suggested by clouds 
in the atmosphere of Mars. If the snow-caps melt 
we should expect clouds from the evaporated moist- 
ure. The polar snow-caps increase and diminish, as 
might be expected, during the long summer and 
winter seasons of the planet. We have no means of 
knowing whether the air of Mars, in composition 
and density, would be suited for breathing by beings 
like ourselves. 

Owing to the small size of Mars, it has no doubt 
cooled nearly or quite through, but still the density 
of the planet is less than that of our earth. 

When speaking of the asteroids, w r e spoke of the 
force of gravitation as dependent upon the mass of 
the body in question. As Mars is but half the size 
of our earth, its attraction of gravitation is but half 
as strong as we know here. Anything weighing a 
pound here on the earth's surface would weigh but 
half a pound in Mars. If here one can lift a ball 
weighing fifty pounds, there, with equal ease, one 
could lift a ball weighing one hundred pounds. 

Walking, jumping, any activity would be but half 
as fatiguing upon Mars as here. On the other hand, 
the circulation of the blood, the action of heart and 
lungs would be so violently increased that beings 
constructed as we are might be unable to exist in 
such circumstances. 



94 B8tronom£ 

As our earth and its inhabitants have been so 
carefully adapted to each other, we may conclude 
that if there are inhabitants in Mars equal harmony 
exists between them and their abode. 

Either from its red light or its name, the ancients 
thought Mars a very cruel and dangerous planet, the 
cause of nearly all of the disease, war, famine, and 
misery upon earth. Mars and Saturn were regarded 
as a pair of twin demons, full of evil influences. 

Why is Mars so alarmingly red ? 

Some have suggested that the vegetation of Mars 
is red and perennial ; others fancy that the earth 
and rocks are of a deep red. The " water lines " on 
Mars are bluish ; the polar caps are white. Thus 
Mars is a kind of American-flag planet — red, white, 
and blue. 

The year 1892 was very favorable for the study of 
Mars, as the planet was nearer us than it will be 
again before 1909. Sixty-eight drawings of the disc 
were made. From these maps we find that Mars 
has more land than water. Also on the surface 
were found some remarkable straight lines, which 
seem to be water, and are known as the " canals of 
Mars." 

As Mars is further from the sun than our earth, 
and is no doubt cooled quite, or nearly quite through, 
we might expect it to be colder than our earth. A§ 



TRefc flfcare 95 

far as we can discover from telescopic observation, 
however, the climate is much the same as here. 

The state of the ice caps on the Martian poles gives 
some indication of the temperature. We find that 
these shrink, by melting, during the long summers. 
We also find that the equatorial regions of Mars 
seem to be free of snows, as are the tropics of this 
world. 

On the whole, Mars has proved one of the most 
interesting and useful objects for astronomic studies, 
and, as telescopes improve and observers increase, we 
are likely to know more and more about it. The 
nearness of Mars has given rise to many extrava- 
gant suggestions and romances. It has been said 
that in some way communication could be opened 
between Mars and the earth. Any inhabitants of 
Mars must have intellects, and any intellects would 
recognize a geometrical figure ; therefore, if men 
built on some vast plain — as the Sahara or a South 
American pampas — a proposition from Euclid, the 
Martian-men would recognize it as an output of 
sense on the part of Earth-men and would reply in 
kind! 

Another proposition has been that as Mars is much 
older, in all probability, than our w r orld, it must have 
been much longer inhabited, and the Martian people 
have had time far to surpass us in all know r ledge ; 



96 Batronom^ 

discoveries, and inventions. Therefore being so 
much wiser, they will soon find some way not only 
of opening communication with our earth, but of 
getting here. In fact, the Martians must be eager to 
reach here, because owing to its greater age, smaller 
size, and longer distance from the sun, Mars must be 
not only too cold for comfort, but too cold to live 
upon at all, and its inhabitants must be anxiously 
looking about for a place to colonize. Many people 
in the United States have been complaining bitterly 
about the influx of emigrants from Europe and Asia ; 
if, through the skies, emigrants from Mars begin to 
drop upon us like a storm of hail, or even like the 
large silent flakes of a snow shower, a wail would be 
lifted from all the world. Our only hope would be 
that our climate would be so much too hot for them 
that they would perish, unless they hastened their 
departure. Even the poets have indulged in absurd- 
ities about Mars. Mr. Kipling considers him as a 
horse wildly careering through the skies, and says : 

" Hanging like the reckless seraphim 
On the reins of the red-maned Mars." 

Professor Holden thinks that if by " reckless 
seraphim " the poet means star-gazers, that he is 
quite right, and they have been more than reckless 
enough. Really scientific men are careful not to be 



IRefc /tears 97 

hasty in statement, nor to indulge in theories at the 
expense of assured facts. Careful observations made" 
at the Lick Observatory in 1895 raised a doubt 
whether there were as much water on Mars and in 
its atmosphere as had been hitherto supposed. 
Observations made by spectroscope at the observatory 
at Mount Hamilton show that Mars is amazingly 
like our moon, and if it should prove that Mars is in 
the condition of our moon, dry and cold all through, 
then verdureless and waterless, all question of " men 
on Mars " will be finally set at rest. 

When Mars is in sight anxious amateurs and 
astronomers spend their time in observing it ; when 
it is lost in its sun-bath, drowned in light, they spend 
time talking and writing about it ; all this considered, 
it seems that we really ought to know more about 
Mars than we do I Professor Young considers that 
the Martian canals are real and that great changes in 
them accompany the waxing and waning of the 
polar ice-cap of Mars ; he thinks also that, as com- 
pared with ours, the atmosphere of Mars is very rare. 

Mr. Lowell, possibly because he was writing charm- 
ing papers for a magazine, directed to a not critical 
public, theorized that Mars has no hills, no moun- 
tains, is a dead-level land like Egypt, and that the 
melted snow-caps send still floods over all its surface, 
carrying fertility with them. He holds that the dark 
7 



98 :astronom2 

spaces are not seas but plains covered with dense 
"forests. He also thinks that the canals of Mara 
must be artificial because they are so straight, and 
that what we see is not the canal with its waters, but 
the exuberant vegetation beside' them. From the 
size of these canals, which he claims must be artificial, 
he asserts that the men who made them must be 
gigantic ; and that these huge men must have a 
strength a hundred times greater than the inhabitants 
of ou£ earth, and an infinitely greater knowledge of 
mechanical appliances. On the whole, after hearing 
all this, we feel very glad that so many millions of 
miles lie between us and " the red planet Mars." 

Professor Young calmly remarks that against all 
these theories of Mr. Lowell stands the fundamental 
doubt whether so small and distant a planet can have 
anywhere more than a life-destroying coldness of 
temperature, and another doubt, namely, whether the 
ice-caps are ice at all or some substance quite dif- 
ferent. The observatory of Mr. Lowell is in Arizona, 
and continuance of telescopic work there has con- 
vinced him that " Mars does not present the same 
appearance for two successive seasons, and the 
differences are not confined to details but to large 
and prominent features " upon which at times 
theories have been founded. Thus it seems that our 
red neighbor in the skies is a very shifty and deceit- 



IRefc /Hbars 1)9 

ful planet, and no dependence can be placed upon 
his revelations concerning himself. The fact is, that 
we should remember that in all observations made of 
the heavenly bodies the earth's far extended atmos- 
phere must count for something, and lines might 
seem to be upon the planet under observation, when 
really they were to be attributed to some action or 
condition of the earth's atmosphere, and it is only 
many times repeated observations of the same regions 
of any body that would correct errors which arise 
from our own conditions. 



CHAPTER X 

GREEN EARTH 

"Brightest seraph, tell 
In which of all these shining orbs 
Hath man his seat?" 

Where shall we make our journey to-night? we 
ask. We shall stay closely at home to-night. Our 
Earth is the planet next in order of formation as we 
travel sunwards from Neptune through the ranks of 
the solar family. 

After that glowing ring which coalesced into Mars 
was cast off , we do not know how long the sun 
rested before a ring seven times as large went wheel- 
ing into space. When this new ring arrived at a 
distance of some ninety-one or two millions of miles 
from the sun, it was stayed by attractive force getting 
the better of tangential force. Turning over and 
over in the direction from west to east, w^hich it had 
received from the sun, this ring came together into 
a ball, continued to make a revolution upon its axis, 
and to swing in a great orbit around the sun. 

The orbit of the new planet was elliptical, like the 
orbits of the other planets. The concave side of the 
100 



<3reen jEartb 101 

ellipse is always toward the sun. The rotation of 
the earth on its axis occupies twenty-four hours ; 
the synodic, or yearly journey is a little ever three 
hundred and sixty-five days. If the plane of 
the earth's motion were not inclined, or, as we 
might say, tilted, to the plane of the ecliptic or path- 
way, the days and nights would be of exactly the 
same length the year around. This inclination, to- 
gether with the time of its trip through its elliptical 
orbit, produces the seasons. We have four seasons, 
each of three months duration. 

If the earth turned over and over, but did not 
travel about the sun, there would be only one 
season. Such an " if " could not occur, because if a 
planet did not travel along an orbit about the sun, as 
soon as tangential force was exhausted attractive 
force would be so strong that the planet must tumble 
back into its source. But for the restraint exercised 
by the swift roll in an orbit the moon would have 
tumbled back into the earth, the earth and the other 
planets into the sun again. So the sun would 
have been like the fabled monster-god Saturn, who 
devoured his children. 

The turning of the earth on its axis causes one 
side to be presented to the sun, while the other side 
is in shadow ; we call that shadow night. With the 
turning of the earth, that line of shadow moves slowly 



102 BsttonomE 

along the surface, night passing into day as it moves. 
When, owing to its inclination, or tilting on its 
axis, more of the earth's surface is exposed to the 
sun. the days of that exposed portion are longer ; 
when a part is tipped away from the sun the days 
in that portion are shorter. It is this tipping, or 
inclination, which causes the sun to seem to be in 
the south sky during winter, and to the north in the 
summer. 

It occurs to us to ask why the earth moves from 
west to east, when it seems to move from east to west ; 
that is, our earth seems to us to stand still, and the 
sun to move, and the sun appears to move from east 
to west. We have all been on the steam cars moving 
out of a depot. As the train started quietly, it 
seemed to us that the train next us was moving, and 
our train was standing still. Or. when our train 
stood still, and the train next us started, it seemed 
as if our train was in motion and the other at rest. 
As we are on that moving planet, the earth, it seems 
to us to stand still, while the sun, which, so far as we 
are concerned is still, seems to be journeying swiftly 
about us, as the ancients supposed to be really the case. 
Again, when we have traveled in the cars, trees and 
houses seemed to us to be rushing, not with the train, 
but back toward the point of starting. Thus, as 
our earth-motion is swiftly from west to east, it 



<5reen JBartb 103 

causes the apparent motion of the sun from east to 
west. 

Having settled this point, we need to know more 
about night and day. 

Here, in the first place, is a little experiment 
which we have arranged for illustration. On a rub- 
ber ball are painted two wdiite poles, a red equatorial 
region, and two green temperate zones. We have 
run a long hat-pin through the axis of the ball, and 
hold it tipped, as the earth is tipped, to the plane of 
the ecliptic. Now, here is a long cone of paper, 
which fits upon the equator of the ball. We pin this 
gilt star to some fixed place to represent the sun. 
The cone represents the shadow cast by the earth. 
The exposed part of the ball lies fair to the sun, and 
represents day. Hold the cone steadily upon the 
side of the ball opposite the sun, that represents 
night ; the opaque earth shuts off the sunshine from 
that half of itself. Now, slowly revolve the ball 
upon the pin ; some of the part that has been in the 
cone-shadow creeps out, and equally some that has 
been exposed creeps in. The side which was in the 
light at first had a blue 1 upon it, and the side within 
the cone a yellow 1. Now we see the blue 1 is in the 
night-cone, and the yellow 1 has crept into daylight. 
The days of our northern half of the world are at 
their longest at mid-June, and are shortest at mid- 



104 Bstronoms 

December. At the equator their length is more 
nearly equal, and they do not have the long twilight 
at dawn and sunset that we have. 

Like the other planets, our earth is round, bulging 
at the equator, and slightly flattened at the poles. 
All heavenly bodies but comets have this round 
shape. The sun, the moon, the discs of the planets, 
exhibit this rotundity. Comets seem to have roundish 
heads, from which stream back tails or trains of 
burning vapor. 

The ancients supposed the earth to be a flat, circu- 
lar plain. Several simple illustrations prove to us 
its rotundity so clearly that we wonder that it was 
ever doubted. 

From some balcony we have watched the ships 
putting out to sea. If they disappeared on a level 
plain, merely because they went out of the reach of 
our vision, a ship would, as a whole, grow smaller 
and smaller, and so fade from sight. Instead of this 
the hull sinks out of sight first, while the tall masts 
remain in view for some time longer. As says Cole- 
ridge : 

" The ship was cheered, the harbor cleared, 
Merrily did we drop 
Below the kirk, below the hill 
Below the lighthouse top." 

Fancy that a pin stuck in our rubber ball repre- 



<3teen Bartb 105 

sents ourselves, and a little peanut shell with a 
splinter for a mast is a ship sailing away. We keep 
our eyes on a line with the pin's head. As the shell- 
ship moves down the roundness of the ball we lose 
sight of it, but the little mast is in view somewhat 
longer. When steamers come toward us along the 
sea we see the smoke from the funnel first, then the 
funnel, and then the hull. 

Another proof of the shape of our earth is that its 
shadow cast on the moon in an eclipse is round, and 
like the shadows cast by other planets which we 
know to be spheres. We can also prove the rotundity 
of our earth by measurements which are too difficult 
and abstruse to suit our present purpose. 

The surface of this globe, the earth, is composed 
of land and water, about one-fourth land and three- 
fourths water. The diameter of the earth is nearly 
eight thousand miles, and its circumference twenty- 
four thousand. It has polar caps of ice and snow. 

Early in its history our earth cast off a gaseous 
ring, which became a globe and travels around the 
earth, as its moon or satellite, at a distance of two 
hundred and forty thousand miles. The difference 
in size between the earth and the sun has been 
likened to a grain of mustard-seed revolving about 
a cocoanut. If the sun were a hollow globe and 
the earth were set in its centre^ with the moon 



106 Bsttonoms 

whirling about it two hundred and forty thousand 
miles away, there would be very nearly as much 
distance still left between the moon and the shell of 
the sun as there is between the earth and the moon. 

The crust of the earth is solid, being formed of 
rocks and w T hat we call earth, or mold, made of 
ground-up rocks and decayed vegetable matter. 
The rocks and sand form vast basins wherein are 
bodies of water called seas and oceans. Evapora- 
tion from the surface of the earth condenses into 
clouds, which are always in our atmosphere. Our 
earth has more clouds than Mars, but not nearly so 
many as Jupiter. 

While the crust of the earth is solid it is generally 
supposed that within that crust are several layers of 
matter of different densities about a gaseous core. 

The mass and density of the earth have been 
many times measured. During 1893 Professor 
Berget in France made a new measurement, which 
was distinguished from others by the freshness and 
beauty of its method. Berget borrowed a lake from 
its owner, Monsieur Curel. The lake was artificial, 
was eighty acres in extent, and had water-ways and 
gates by which its level could be rapidly changed. 
This lake was at Habay-la-Neuve. Berget had an 
instrument for measuring the force of gravity. This 
instrument has a column of mercury " balanced 



<3reen Bartb 107 

against the elasticity of a certain confined body of 
hydrogen/' both shut up in a vacuum, and kept in 
a constant temperature. Now, just as in a ther- 
mometer or barometer, a change in the temperature 
or moisture of the air causes a rising or falling of 
the mercury inclosed in a tube, in this instrument 
the mercury is moved by the least change in 
gravity, and the gravimeter, or gravity measure, is 
capable of registering so small a motion as the one 
hundred millionth of an inch. 

Professor Berget, by means of the water-ways and 
gates, lowered the level of the lake somewhat over a 
yard — one French meter — and then examined the 
change in gravity registered by his instrument to 
see what was the value of that amount of water 
in gravity or pulling force. Measurements in 
gravity and density taken before were not changed 
by this new method and its results. The interest 
lay in the curious delicacy of the instruments used 
and the originality and simplicity of the plan. 

" I don't see," said a thoughtless person one day, 
" why any one cares about the density of the earth 
or the force of gravity. What does any one want to 
know about it for? What difference does gravity 
make to me? Suppose the force of gravity should 
change all in a minute, who would care ? Who would 
know it?" 



108 B0ttcmom£ 

There is a deal of absurdity in such talk, but 
we answer: Every one would know it, could not 
help knowing it, and would care a good deal. It 
is a fortunate affair that the laws of the jmiverse 
are reliable, unchangeable, and there is no dodging 
them, no shirking of their consequences. Let us 
suppose that the attraction of gravitation could all 
in an instant double. Then all power needed to 
effect any result would need to be doubled. It 
would require twice as much effort to lift the foot 
from the ground to make a forward step. One might 
well say then that " my feet felt as if made of 
lead." One would soon grow weary at that rate. 
The weight of every object would be doubled. If 
one were buying ten pounds of sugar and had paid 
for that amount one should receive for the money 
what had hitherto passed for five pounds. The 
wheels of the cars would rest so much more heavily 
on the track that two engines would be needed to 
do the work of one. If one fell, one would come 
down with twofold violence, and so on. 

Suppose, on the contrary, the pull of gravity sud- 
denly lessened by one-half, then the barrel which 
had held two hundred pounds of flour would hold 
but one hundred by the new weighing ; a student 
devoting himself to athletics would be charmed to 
find himself making a " standing high jump " that 



(Breen JEartb J 09 

beat all known records : a ball tossed high might sail 
out of sight and leave its small owner weeping ; the 
axe brought down with customary stroke on a billet 
of wood would be endowed with so little force that 
it would make but a small cut. " The times would 
be out of joint " for us, sure enough, and all our cal- 
culations overthrown. 



CHAPTER XI 

THE EARLY DAYS OF THE EARTH 

"A boundless continent, 
Dark, waste, and wild, under the frown of night, 
Starless exposed." 

" What I want to know is," says some one, " why 
this force of attraction, pulling together a ring of 
matter, always makes a ball-shape." 

Because the pull is even all around the common 
centre — the centre of gravity. Just as much mate- 
rial is pulled at one place as at every other. This, 
of course, causes roundness. 

Yet the planet balls are not even or round, abso- 
lutely ; they are flattened at the poles and bulged at 
the equator. We will try to illustrate, first as to 
the roundness, then as to the deformity. Gravita- 
tion causes all liquids to assume a round shape in 
falling. A drop of water is round. If you put a drop 
of thick oil into water, with which it cannot mingle, 
the drop of oil remains round, suspended in the water. 

Let us consider how they make shot. High towers 
are built, called shot-towers. The melted metal is 
poured from the top of the shot-tower, and falling 
110 



£be EarlE Base of tbe Battb 111 

to the ground it cools in its descent into round 
evenly-made shot. The size of the shot is regulated 
by the meshes of a sieve on the top of the tower, 
through which the molten metal is poured. The 
shot fall into a tank of water, where they complete 
their cooling. Shot towers are from one hundred 
and fifty to two hundred feet high. 

This story of the shot shows us how liquid or 
gaseous or other soft bodies are pulled by gravitation 
into roundness. As to the bulging and the flatten- 
ing, which deform the roundness, they come in this 
wise : The shot being so small, cool almost instantly, 
keeping their round shape; but planets, even the 
very smallest, are immense bodies of intensely heated 
gaseous matter, and cannot cool quickly. Each turns 
upon its axis, and whirls through its orbit in a state 
of incandescence. Continuing these double motions, 
" turning over " and " getting on," each sphere cools 
and solidifies slowly. 

Imagine a ball of soft material set to whirling very 
simply ; fancy you were spinning a ball of half 
cooled molasses candy upon a string. The conse- 
quence of the swift rotation would be a bulge in the 
circumference, a drawing in of the poles through 
which the string passed, and presently such an over- 
weighting at the ball's equator that some material 
would begin to fly off. 



112 Sstronom^ 

As there is only just so much material to account 
for, it is plain that where it swells at the equator it 
must shrink at the polar part, that is, farthest from 
the bulge. When the planet ceases to cast off ma- 
terial, and cools into permanent shape, the " de- 
formity of the sphere," as it is called, that is, the 
equatorial enlarging, is a fixed feature. 

How about the shape of the sun? That seems to 
be perfectly round, we say to ourselves ; but do ap- 
pearances deceive? It seems so, because of its 
enormous size ; the sun has such equatorial enlarge- 
ment, and polar depression as the planets exhibit. 
The extreme slowness of the sun's motion has 
prevented this deformity from being as marked as 
in some of the planets which rotate most swiftly. 
To on-lookers from distant nebulae the rule of planet 
shape would seem uniform. How, we wonder, does 
our earth look to people on Venus — if there are any 
there — with telescopes ? 

Very much as Mars appears to us, except that it 
is larger and has a more clouded atmosphere. They 
se,e the polar snow-caps and the attendant moon. 
Some have suggested that just as the light of Mars is 
red, the light of our earth is a pale green, from our 
green vegetation, and our seas might shine like 
molten glass or Alpine glaciers. We wish one could 
tell us all about the way in which the earth has 



She £arls Bav^ ot tbe Bartb 113 

changed from a ball of gas to what it is. Suppose 
we could see it just like a panorama, a splendid 
succession of scenes. We can trace a little of the 
little that is known about it. We will remember, 
meanwhile, that the changes which we describe are 
probably those which sooner or later will overtake 
all planets, and are now in progress upon them in 
different degrees. We see great Xeptune. Uranus, 
Saturn, and Jupiter in their various states of heat 
and fluidity, and we argue that our earth, as a planet 
of like motions, shape, origin, and materials, has 
passed through the same stages. We might reason 
in another way also, that as our earth has now a core 
of very hot material in a fluid or gaseous state, we 
can infer the change from that hot core outward in 
all its different stages. 

We know that our earth has a heated core, because 
in mines carried to a great depth the heat is almost 
unendurable. Yet the deepest mines enter but a little 
way into the earth's crust. Volcanoes, boiling springs, 
or geysers are known in ail parts of the earth, from the 
polar circle to the tropics. Many of the islands and 
mountain chains are of volcanic origin. Frozen 
Iceland has violent volcanic eruptions. Its boiling 
springs leap up from one to two hundred feet into 
the air. These jets of boiling water, these floods of 
red-hot lava, these veins of fiery ashes, all show that 
8 



114 Bstrcnom^ 

the inner part of the earth from which they come 
must be in a molten condition. 

The surface of the earth is cool to the touch, yet from 
it the interior heat is always imperceptibly oozing. 
We have, perhaps, visited a brick-yard ; we know 
that a big brick furnace is built, in which they bake 
bricks and tiles. The thick walls of this furnace 
keep in the heat, so that it bakes the bricks red-hot 
through and through. Yet the kiln does not keep 
in all the heat. The outer wall feels warm to the 
hand. Heat is oozing from it, little by little, and 
the air carries it away. 

In the same fashion from the surface of the 
earth the heat of its inner fires constantly passes, and 
each age the earth is cooler and cooler. We have 
no idea how many thousands of years this cooling 
process has been going on. The Creator never hur- 
ries His work. 

The earth, as it has cooled and shrunk so much, 
must now be smaller than when it was cast off by the 
sun. It is much smaller in extent ; but we need to 
remember that its weight has always been the same. 
Cooling and shrinking do not change weight. The 
weight of a piece of iron does not change, whether 
the iron is at its smallest size, perfectly cold, or is 
expanded by being red-hot, or white-hot, or still 
more expanded by being melted. The earth always 



Zbc Barlg Ba£g of tbe Bartb 115 

weighed what it does now ; therefore its attractive 
force was never less than now. Cooling, shrinking, 
and hardening have changed the state of the ma- 
terials and the size, but the matter is always the same. 

The earth constantly loses, but never gains any 
heat. The heat we receive from the sun radiates 
from the earth's crust, and never penetrates it very 
deeply. Think how soon the night shadow cools 
off the heat of the hottest day. Winter presently 
causes us to forget the heat of the hottest summer. 

We know really very little of the interior of our 
earth. Great chasms or cracks in its surface, are, in 
comparison, no more than the little lines on the rind 
of an orange. Our deepest mines are, in comparison 
with the diameter of the globe, no more than the 
tiny dent you can make with a pin's head in the 
orange skin. In spite of all this, careful study of the 
small portion that is open to our inspection has 
enabled us to read the history of the whole. 

When t>ur earth first assumed spherical shape it 
was a huge ball of gas, probably two thousand times 
as large as it is now, all its materials being at their 
state of utmost expansion. This mighty globe of 
glowing vapor whirled and cooled, and the core, by 
pressure, became fluid. The outer portion acquired 
what is called a photosphere, or visible shining sur- 
face. This may be the present state of Neptune, 



116 Betronomg 

After a great lapse of time, by constant cooling 
the photosphere darkened, and a more or less solid 
crust was formed. The next state was probably that in 
which we now find Jupiter, the atmosphere violently 
stormy and full of clouds. After that would come a 
period of water forming and depositing, until the 
whole surface of the globe was under water. Do we 
ask, " Why are Neptune and Jupiter and other planets 
probably in a state that our earth passed long ago ?" 
They were probably formed a great while before the 
earth, not only that, but they are enormously larger. 
Cooling and hardening would require many more 
ages in such immense masses of material. After 
the water envelope of our earth was formed, we sup- 
pose that the crust under the water continued to 
cool and to thicken, then cracked and broke by 
shrinkage and the force of interior gases, steam, and 
molten matter. Being so rent, the crust was lifted, 
forced, tilted up by action of the interior elements. 
It rose above the waters in peaks, ridges, levels, and 
tilted sections. This lifted rocky crust became the 
foundation of future continents. 

After many more ages the action of water and 
storms had corroded and ground up portions of rock 
into clay, sand, loam, marl, all that we now call 
earth. Thus the surface of the rocky continents 
was covered more or less deeply with material fit 



Zbe JEavls Ba^e ot the Battb 117 

for vegetation, while the waters in the ocean beds 
had cooled sufficiently to become the abode of 
animal and vegetable life. Such life was in the 
water long before it appeared upon the land. The 
formation of land was very slow, accompanied by 
rising and settling of tracts of earth crust. Some 
of the substances just mentioned as composing soil 
were remains of generations of animal and vegetable 
life. 

When this stage of fitness for life was reached the 
story of planet-building was nearly all told for our 
earth. It is a question often asked : kk How long was 
this process of earth-building? How old is our 
earth?" Perhaps no question-was ever asked that 
has received such widely differing answers, many of 
those answers being given as veritable scientific 
statement and demonstrated by mathematical cal- 
culations, based on certainties of physics. The age 
of the earth may be said to be written in its geologi- 
cal strata, but it is by no means written so plainly 
that he who runs may read it. The wisest differ 
greatly in their estimate of how long it takes for 
certain changes to occur. How long will it be be- 
fore heat and pressure turn sand into sandstone? 
How many ages will be required for the waters to 
deposit in a fine rain of particles upon the floor of 
the ocean the comminuted shellv bodies of fora- 



118 BettonomE 

minifera until the great beds of limestone rocks 
were ready as a cheese for pressing? Some savants 
affirmed one period of time as needed for such radi- 
cal changes in the state of affairs, and some another. 

But long before shells, or sand, or other such 
now known material was, long ages were required 
for the ball of blazing, glowing gas to cool, contract, 
become semi-fluid, liquid, solid. Proceeding on 
calculations of temperature and the time required to 
change to a solid state from complete fusion, other 
wise men demanded say a hundred million of 
years. Now, w T hen so many years as a hundred mill- 
ion are in question, a matter of forty or fifty, or 
even a hundred million more is but a trifle, so some 
concluded that three hundred millions of years 
would not be time too long for so vast changes, and 
others, equally as wise, asserted that from fifteen to 
thirty millions of years would give quite time 
enough. 

"It is forty-five millions of years," says one, 
" since the globe was cooled and framed into a pos- 
sible home for some forms of life ; the first fossils 
date from forty-five millions of years ago." Thus 
the argument goes on, results forever changing, all 
that remains assured being that very long time — ■ 
time beyond any possibility of real comprehension — ■ 



TLhe Barl£ S>a£9 of tbe JEartb 119 

was needed in world-building. Ar£, then, these cal- 
culations and discussions wasted? By no means. 
Physics has come to the aid of geology, curbing ex- 
travagance of statement. It has been seen that 
accurate data have not yet, and, perhaps, never can 
be obtained, but that from widely differing premises 
conclusions not widely divergent may be reached, 
and in this searching after data for time statements 
many valuable discoveries have been made and the 
sum of human knowledge greatly increased. 



CHAPTER XII 

THE EARTH'S DAUGHTER 

"And treat her as a ball, that one might pass 
From one hand to the other." 

Here is a great, fair, full moon, all ready to be 
talked about, a " hunter's moon " hanging full and 
low ; a red harvest moon ; or a round, steadfast, clear, 
cool, summer moon ! How near she looks ! It 
seems as if one could shoot an arrow to her. Yet 
we are told that she is two hundred and forty 
thousand miles away. It is hard to realize or believe 
in these distances. But then this distance is so short 
in comparison with the space that divides, us from 
other heavenly bodies that we call the moon a near 
neighbor, and large telescopes have made her surface 
very well known to us. We know her as well as we 
know some parts of our own globe. For instance : 
What are those dark lines, like mountains ? They 
are mountains, great volcanic peaks and ranges. 
The whole moon-surface is a series of burnt-out 
craters. The nearest likeness which we can find to 
moon scenery is the upper portion of Mount Vesu- 
vius. After you have passed the limit of vineyards 
120 



Gbe 3£artb's Baugbter 121 

and cottages, you come upon a great broken slope of 
loose lava, ashes, scoriae, and large lumps of volcanic 
rock. Not a blade of grass is seen in that silent, dry 
desert. Your feet slip in the loose material, old 
embers of dead fires. You come to the ragged- rim 
of the crater, and look down into the great rough, 
broken bowl. 

You cannot descend into Vesuvius, cross the 
crater, and come up on the other side of the rim, 
for the volcano is too frequently active, and the crust 
within the bowl is hot and thin. 

The moon volcanoes were long ago burnt out, and 
if one could walk about the moon, one would find 
no hot lava. In fact, a traveler in the moon must 
be going up and down the crater sides, and across 
the lava fields all the time, for that is all the land- 
scape there is. Looking at the moon we ask : " Has 
the moon had all the changes through which the 
earth has passed, from gas to fluid, then to solid?" 

Most of them probably. Whether it ever reached a 
stage of habitable surface, such as our earth seems to 
be resting in now, we cannot tell. Perhaps those 
tall moon volcanoes which are like hollow cones 
with the tops cut off, were once in the flaming sur- 
face of the moon just such spots as we see now in 
the sun, and marvel about. The whole surface, so 
far as we know it, seems to be volcanic. Is the moon 



122 BstronomE 

of any use, but to give us beautiful, light nights ? 
What effect has this truant child on the mother orb ? 
It causes the tides and the tides are of immense value 
to commerce and navigation. Many of our greatest 
seaport cities could not be approached by ships of 
any large size were it not for the help of the tides, 
each day giving deep water in the harbors. Many 
fishing fleets depend on the daily tides for their 
going and coming. Many of the great cities also 
depend on the tides to flush and clean out their 
sewer systems. 

Some people think that the moon has much to do 
with the weather, and others talk of its influence on 
the growth of vegetables, and of " planting in the right 
time of the moon," but that is all a mistake, the 
moon has no influence at all in these directions. 

Although the moon appears so large, quite as large 
as the disc of the sun, it is really the smallest visible 
object in the skies. Its nearness makes it seem large. 
It would take fifty moons to make a globe of the 
size of this world, and fifty million moons to make 
a sun. As to weight, the material of the moon is 
lighter than that of our earth, and eighty moons 
would be needed to turn a scale against our globe. 

The moon travels around the earth in its orbit 
in twenty-seven days, and what we may think 
very strange is, turns over on its axis but once 




A NEAR VIEW 



Gbe Bartb'a Daughter 123 

in twenty-seven days also! The sun's rotation on 
its axis is accounted slow, taking twenty-five days^ 
but the moon demands about twenty-seven days and 
a quarter for one revolution. 

In consequence of the rotation of the moon being 
made in the same time as its orbital journey, we 
never see but one face of the moon. The other half 
is never toward the earth. There has been a deal of 
speculation as to what that unseen half of the moon 
is like. There are periods in the orbital journey when 
a little rim of the moon beyond the face constantly 
turned to us is to be seen on one side or the other, 
and as that portion shows the same volcanic desola- 
tion as the side we know r so well, we conclude that the 
entire moon body is in the same state of barrenness. 

We do not know whether the moon has cooled all 
the way through, or whether it has a core of soft 
lava. At all events, volcanic action has ceased in 
the moon for long ages, and no doubt the hardened 
crust is too thick to permit any eruption, even if 
there are interior fires. 

Long ago the moon was much nearer the earth 
than now. It receded gradually, driven by tidal 
force, as if the earth in its swift revolving, having 
cast off the moon by tangential force, had slowly 
reached out a hand and pushed it gently farther and 
farther away, until its present place was reached. 



124 astronomy 

This distance may still increase, but so slowly as to 
be imperceptible until after long ages. 

"If the moon is the earth's child, it looks very 
ugly in the earth to push her away !" says some 
one. So ? Even a kind and tender-hearted person 
will gently push a child away, if it is treading upon 
them, or crowding them. At first, by its nearness, 
the moon may have made the earth uncomfortable. 
Suppose that it constantly pulled the salt tides all 
over the land ! This recession occurs in all satellites, 
and with the withdrawing, a slowing up of their 
motion. If we were close to the moon, what should 
we see ? A planet without a drop of water on 
its surface — not a drop of dew. No place on the 
earth is so dry as the moon is. The earth has alwa} T s 
some moisture in the air, the moon has no moisture 
anywhere about it. Those flat shining places on the 
moon surface, once called seas, are really volcanic 
deserts . 

Our earth is wrapped in an atmosphere some one 
or two hundred miles thick. The moon has no 
atmosphere. Close to its surface there may be some 
gaseous layer, but there is not a waft of air, not a 
fleck of cloud or mist. As there is no dust and no 
vapor, the moon has no splendidly colored clouds, no 
blue skies, no varying tints. Clear light is poured 
from the sun, but there is no diffused light ; no life ; 



Gbe Bartb's Daugbtet 125 

above it or around it, the moon has only black depths 
in which shine and flame stars, comets, planets, the 
sun, the great star. There is no sound to be heard 
on the moon ; no click of moving sand ; no jar of 
falling rock ; no rumble of thunder, all is profound 
stillness. Think of it, a world airless, waterless, 
soundless, colorless, lifeless. To us the moon looks 
bright, with a soft, steady, clear radiance. This is 
because her surface reflects the light of the sun, and 
this light, tossed toward us, is caught and reflected 
by the dust in our atmosphere as a beautiful, stead- 
fast illumination. 

There is no decay, no downfall, upon the moon, 
because air and moisture, the chief agents of decay 
and change, are absent. We discovered that the 
moon had no water when the telescope showed us 
that there were never the least clouds about the 
planet. The evaporation of moisture will always 
produce cloud or mist, The lack of moisture was 
easily shown. How did we find out about the lack 
of atmosphere? When a star is hidden from the 
earth by the passing of any heavenly body between 
the star and the earth, that is called an occupation, 
or hiding of the star. The moon sometimes passes 
between us and a star. When that happens the star is 
suddenly lost to sight, and as suddenly reappears on 
the other side of the moon's disc. If the moon had an 



126 astronomg 

atmosphere, the star would be dimly veiled by that, 
before it was quite hidden by passing behind the 
moon. How simple some of these explanations seem 
after they are made. The nearness of the moon, afford- 
ing so clear observations of her phases and her 
eclipses, early made her an object of interest. What 
is that distance or nearness? We call two hundred 
and forty thousand miles a long way. So it is, but if 
we could traverse it by steam we could reach the 
moon in less than a year. If a stone could be 
dropped from the moon, and set free of its attraction 
of gravitation, it could tumble down to the earth in 
three days, or perhaps four days. It would take 
longer for it to tumble back, because the gravity of 
the earth is greater, and it would not fall so fast at 
the beginning of its journey, nor be pulled so quickly 
at the end. 

The ancient philosopher and teacher, Pythagoras, 
who lived five hundred years before Christ, seems to 
have had views far in advance of his day, on the 
subject of astronomy. It is said that certain sages 
of Egypt and Babylon were his teachers, and that 
he understood that the sun was the centre of our 
solar system, and that all the planets revolved about 
it, the moon only moving about the earth, instead of 
all the heavenly bodies, as w r as then currently sup- 
posed. Pythagoras taught orally, and he did not 



Hbe jEartb's Daughter 127 

think it well to reveal his views of the world-system 
to people in general, but merely to a chosen few of 
his most intelligent pupils ; thus only a very few 
heard from his lips that the sun is the true system- 
centre. A hundred or so of years later, men who 
had learned from the favorite disciples of Pythagoras, 
announced the doctrine of the sun as the centre of 
the universe. They were at once persecuted for 
impiety, and their lives were threatened, so that the 
teachings of Pythagoras were suppressed, and the 
system later taught by Ptolemy was the only one 
advocated. 

Pythagoras had tried with the rude instruments 
known in his time to measure the distance between 
the earth and the sun, and the earth and the moon. 
He concluded that the sun was nearly thirty thousand 
miles off, and the moon about fifteen hundred. 
Proper measurements could not be taken in those 
early times, and it was not until 1769 that accurate 
knowledge of distances in our system was obtained. 
It has taken the observations of many men during 
many years, to arrive at facts which we speak of 
lightly as a matter of course. " One man's w T ork for 
a thousand years could not duplicate them," says 
one astronomer, yet all this knowledge is now our 
heritage. 



CHAPTER XIII 

MORE ABOUT THE MOON 

"The young moon has fed 
Her exhausted horn 
With sunset's fire." 

There are many things we ought to know about 
our night queen. It is easy to see that the moon is 
a round body and travels about the earth, always at 
nearly the same distance, and with the earth goes 
around the sun, but how shall we clearly explain the 
moon's changes ? 

The new moon first appears to us as a thin cres- 
cent, perhaps one-third way up toward the zenith. 
Just before sunset we see that silver bow, and per- 
haps we wonder why, since it is so high, we did 
not see it yesterday. Notice that the concave side 
of the crescent is always toward the east. 

The moon, we know, travels eastward, as the earth 
does, and when we see this crescent, which we call 
the " new moon," she has just passed the sun, and is 
so turned that only a little part of her disc catches 
the light of the sun. The changes of the moon 
from first, second, and third quarter to full are 
called " phases." We shall find that Venus and 
128 



/Iftore about tbe /Iftoon 129 

Mercury, the two planets lying between us and the 
sun, have also these phases. 

The moon continues to advance along her orbit, 
and when she is ninety degrees from the suir\ve see 
one-half of her face illuminated. Whe^ twice that 
distance, or one hundred and eighty degrees, have 
been gained, we have full moon; she is then in 
opposition, or exactly opposite the sun, and thus 
shines splendidly in the east, receiving the sunlight 
full upon her whole face. We see the full moon 
rising at sunset in the east. 



f\ 



K y 




THE PHASES OF THE MOON. 



Still the moon moves on, and now begins to lose 
what she has gained. She is no longer full face to 
the sun, but has so moved on, and begins to grow 
what we call gibbous, a portion of her disc lying 
in shadow. Each night some of the brightness 
seems to be cut off, and each night her rising is later, 
until she shines only in the morning twilight ; then 
passes out of sight in the daylight, drowned in excess 
of light, suddenly to reappear as a crescent, high up 
in the west, 

Why does not the earth cut off the sunlight 
~9 



130 Bstronomg 

from the moon when the moon is opposite the sun, 
on the further side of the earth, seems here to be a 
pertinent question. It would do so were it not for 
that tipping to the plane of the ecliptic of which w r e 
have so often spoken. This is the tilting of the orbit 
in such fashion that the sunlight strikes just above 
or below the earth, and so can fall fairly upon the 
moon. It is only planets lying between us and the 
sun that can exhibit to us these phases. 

A question often asked is why the moon turns 
over so slowly? Sir Robert Ball tells us that the 
slowness is caused by tidal action, and that tidal 
action is created in the moon by the attraction of the 
earth. Once upon a time the moon was not a globe 
of burnt-out volcanoes, as at present, she was a soft, 
yielding mass of hot material. In that soft mass the 
strong attraction of our earth created great tides. 
That was long, long ages ago, w T hile our world was 
building into its present condition. The tides ex- 
cited on the moon were not the gentle, changeful 
tides we know on earth, because the body creating 
them was so much greater, and the body in which 
they were created was so much smaller and in a 
softer state. They were tremendous tides. 

If the moon had rotated too slowly, those terrible 
tides w r ould have taken her in hand and dragged her 
furiously along to make her keep up with the earth. 



/Ifcore about tbe /Ifooon 131 

making one rotation while she made one circuit. 
If the moon had been in a hurry and had begun to 
tumble over and over in swift rotations, making sev- 
eral turns during her orbit, these tides, being created 
by the earth, and not mere private affairs of the 
moon, would have held her back, as by the laying 
on of strong hands, so that she could make but one 
rotation while going around the earth. As these 
tides were raised by the earth they were in their 
action tied to the earth. 

Since the moon has grown cold and hard, and 
there is not this wild wash of tides upon her, w T hy 
does she keep up this way of moving ? 

It has been suggested that although now there are 
no tides on the moon, there may still be strong tides 
in the moon. Also there is always a tendency 
toward a state of permanence, or a resting point, for 
long ages before changes again become apparent. 
Nature's laws work slowly and cover periods long 
beyond our imaginations. 

The fact of but one rotation during one circuit 
causes the moon to present the same face to the 
earth at all times. This is easy to state, but it is not 
easy to understand at first. 

Many illustrations have been offered, some of 
which will here be given. This is one : Suppose a 
boy started on the line of the equator and moved 



132 Bstronomg 

entirely around the earth. We will suppose him to 
be a boy able to float gently along in the air, superior 
to such little matters as seas and mountains. This 
boy is flying a kite. When one flies a kite, only the 
front side or face is turned to the one who holds the 
string ; he does not see the back of his ftying kite. 
The moving of the boy around the world, as he flies 
his kite, w r ill cause the kite to make one circuit of 
the globe also, and during that circuit only the face 
of the kite will be seen. The moon is the earth's kite. 

Here is another illustration : Hold a pencil per- 
pendicularly. Let the point represent the earth. 
Let a silver dollar represent the moon. Put the dollar 
against the tip of the pencil, the nose of Liberty 
pointing to the pencil. Then turn the dollar slowly 
about, so that it moves around the pencil tip, and 
still it is the nose of Liberty that is directed to the 
pencil. If there were a hole through the dollar and 
a peg through the hole you would see clearly that as 
the dollar is passed around the pencil it had turned 
once on its axis. 

Again : Take these two apples ; let the larger be 
the earth. Put a hat-pin through it, for an axis 
to turn it upon, and tilt that axis. The little 
apple, also on an axis so it can turn over upon itself, 
represents the moon. Put this small peg in the 
side of the moon-apple that is toward the earth. 



/Hbcte about tbe /Ifcoon 133 

Now move your moon about the earth, letting it 
rotate on its axis once. When it is one-quarter of 
the way around, turn it over one-quarter. When it 
is one-half, turn it one-half. If you tilt your moon- 
axis properly and imagine the knob on a near chair to 
be the sun, you can also see how the sun's light will 
strike the moon in its path, causing its phases. 
Now, when you have moved your moon around the 
earth it has rotated once in the circuit, and that 
peg has been turned to the earth all the tinie. 

By trying such little illustrations one will finally 
see clearly that if the moon rotates once while it 
travels its orbit once, it must keep the same face 
earthward. Xow we begin to see it, and this is one 
of the ideas which, rising in the mind, gain form and 
clearness by contemplation. 

Let us pass to the consideration of whether the 
moon has ever had any atmosphere. It is supposed 
that as all other planets seem to have an atmosphere, 
the moon must once have been so provided. Then 
how did the moon lose its atmosphere ? It is ex- 
plained thus. Air is chiefly composed of two gases, 
oxygen and nitrogen. It has small quantities of 
some other gases. These gases are made up of tiny 
atoms called molecules. As the great stars are 
larger than fancy can compass, so molecules are 
smaller than fancy can conceive. Molecules are 



134 Bettonomig 

very nimble; never quiet; they are always dash- 
ing about with great speed. Some of them seem to 
become excited, and rush beyond the rest, as does 
the swiftest runner in a crowd. These active little 
molecules about the moon took frantic excursions, 
and the moon's mass is so small that her power of 
attraction cannot pull back bodies which travel off 
at the rate of a mile a second. When molecules de- 
parted so recklessly as that, the moon did not bring 
her truants home. 

By degrees all her molecules went off in a terrible 
hurry and failed to return. The departure of some 
made it easier for the others. In the lapse of time 
the moon was left without any atmosphere at all. 
The attraction of our earth is so strong that none of 
the molecules of her atmosphere can get away from 
her. 

This theory is held by very eminent scientists. 
Some also dispute it, but in so doing offer nothing 
in its place. As Plato says,'" This, then, shall remain 
our opinion until we find a better." 

The moon shines, when full, with so strong and 
clear a light that it seems as if she must be a light- 
giving or self-luminous body ; but in truth the body 
of the moon is dark and its splendor comes from 
that little of the sun's prodigal largess of light which 
the moon intercepts and reflects. It has been esti- 



/nbore about the /Iftoon 135 

mated that six hundred thousand full moons would 
be needed to shine with as great brilliancy as the 
sun, but the probability is that that is an immense 
underestimate. , 

We can prove that the light of the moon is en- 
tirely reflected by the very simple method of com- 
paring the moon with the clouds in some early 
morning, when the moon is still half-way above the 
horizon and the sun is rising ; the moon and the clouds 
are both reflecting the sun's light. We see on such 
an occasion that the light of the moon, or her bright- 
ness, and the brightness of the clouds, is of the same 
kind. 

The apparent size of the moon is nearly constant. 
One well-known astronomer illustrates in this wise : 
" If we place a globe one foot in diameter one hun- 
dred and ten feet from our eyes, it will hide the moon. 
Only very occasionally the globe would need to be 
brought closer or removed farther off to hide the 
moon, whether she appeared as full, half, or crescent. 
If the moon were to drift from us into space, her 
apparent size would dwindle ; if she came rolling 
nearer, her apparent size would increase." 

Although the size of the moon is constant, it is 
very remarkable that she seldom appears of exactly 
the same size to any three persons observing her at 
the same time. " How large does the moon appear 



136 Sstronoma 

to you-?" we ask, and a startling variety of replies 
comes : " As large as a coffee saucer," " As large as a 
dinner plate," "As. large as a car wheel," " Oh, no, as 
large as a cart wheel," and so on. 

There is no time on record when the moon was 
nearer the earth than now ; her present position and 
her present consequent apparent size were attained 
long before earth furnished any moon-gazers. It 
is evident that this constant distance of the moon 
from the earth could only be kept if the moon 
revolved about the earth, for if the moon did not so 
journey around the earth, the attraction between the 
two bodies would bring them together. As the earth 
has been set traveling about her greater neighbor 
the whole power of the attraction is expended in 
keeping the moon in her nearly circular path. If 
this attraction were suddenly released, the moon, 
instead of journeying in her orbit about the earth, 
would begin to drift back into space and never return; 
in a comparatively short time the moon would be 
forever out of sight, and we should have no more 
bright-light nights. Then what would poets, painters, 
and lovers do ? 

The moon as well as the sun has its eclipses. The 
earth shadow creeps over the face of the moon, cut- 
ting off the light of the sun, and then the planet 
becomes dark. There is one remarkably beautiful 



jflft;>te about tbe Zircon 137 

and interesting phenomenon to be noticed in some 
lunar eclipses. The moon maybe so hidden behind 
the earth that not one ray of direct light can fall upon 
it, and } r et the whole moon-ball glows with a dull 
tinge, like molten copper. Why is it that we can even 
in this glow see some of the markings of the moon's 
surface? This light comes from some of the sun- 
beams which, having just grazed the edge of the 
earth, have become bent by the refraction of the 
atmosphere, and their deflected light thus passing 
through the immense thickness of the earth's atmos- 
phere, loses its clearness, and takes on this coppery 
tinge. This effect of our atmosphere on sunbeams 
can also be seen at early morning, or in the " after- 
glow " of evening, when the light is more ruddy than 
at noonday. 

Other matters of interest in regard to the moon 
will be treated under the subject of eclipses. 



CHAPTER XIV 

WHITE VENUS 

" Hanging in a golden chain, 
A pendant world." 

Day is closing, and we have wandered over the 
fields and stopped at the top of a hill to watch the 
sunset. Above a belt of distant woodlands lies a 
band of crimson sky, against which rise, white and 
sharp, the spires of two churches. 

Over the vivid flush of crimson are broad stripes 
of purple, blue, and pale green ; just over the deep 
glow of the descended sun, in a field of delicate saf- 
fron tint, shines a great white star. " Oh ! what is 
that splendid world which was not there last night? 
How has it floated so suddenly out of space ?" 

It is Venus, the evening star. One of the charms 
of this star is its sudden appearance, near the setting 
sun, after having been for some time invisible. With 
its clear white beams, standing out against the brill- 
iant colors of sunset, it seems like a great translu- 
cent bubble. You will see it, near its present position, 
for some clays in great beauty. Venus will be in the 
west for some time, rising slowly higher, and in two 
138 



Tldbite IDemu 139 

or three weeks it will be high in the heavens in full 
magnificence, until late at night. Then its light will 
decline, and the planet will pass out of sight. 

It will not be lost, but moved eastward. Some 
morning, if you will go out on the balcony in the 
pearly gray light of coming dawn, your great white 
star, like a lamp hanging low, will be near the eastern 
horizon, still the most beautiful object in the skies ; 
become the morning instead of the evening star. 
You will lose it after a time, just as you lost it at 
first, and it will return as now — the evening star. 
Thus it will move and change, cycle after cycle. 

Venus is the planet next within our orbit about 
the sun. It is our nearest neighbor, the moon ex- 
cepted. At some parts of its orbit it is but twenty 
millions of miles away from us, at other parts it is 
one hundred and fifty-four millions of miles off. This 
variation in distance accounts for its apparent changes 
in size and brightness. Both these distances are 
enormous, beyond our realization ; yet at twenty 
millions of miles Venus is near enough to often seem 
the most splendid of the hosts of night. 

Venus is the most nearly round of any body in our 
solar system, and has the most nearly circular orbit. 
On account of its being so much nearer the sun, the 
sun seen from the surface of Venus would appear 
twice as large as to us. 



140 BetronomE 

On Venus night and day are practically of the 
same length as ours, for the planet appears to rotate 
in about the same time as the earth. Its orbit, being 
shorter than ours, is traversed in two hundred and 
twenty-four days. 

Venus is* more tipped, or inclined to the plane of 
its orbit, than our earth. As it is this tip which 
regulates the seasons, the seasons upon Venus are 
more sharply marked than ours. The winters are of 
about the same coldness, but the summers are very 
much hotter. Venus has no temperate zones as we 
have on the earth ; the frigid zone extends to the tor- 
rid, but is not so fiercely cold as our polar circles. 
There is no polar ice-cap on Venus ; the shortness of 
the winters and the intense heat of the summers do 
not permit an accumulation of snow. 

Some astronomers think that mountains have 
been seen on Venus, measured and found to be 
twenty miles high. Other astronomers are far from 
sure that this is yet proven. We understand the 
seeing and measuring of moon mountains, the 
moon being nearer seems so much larger, but how 
could they see and measure the mountains, if there 
were any such, upon a planet which distance makes 
so small? Here we come upon some wonderful 
facts about Venus. Venus has phases or changes 
just as the moon has. The planet appears to us 



IKHbite Menus 141 

sometimes full, sometimes as half-round, some- 
times as a crescent. It is upon the inner edge of 
the crescent that mountains have been supposed to 
be seen. Of course, the phases are never noted by 
the naked eye, for the image of the planet cast upon 
our eyes is very small, too small for any such 
changes to be visible. The telescope shows us these 
phases. 

The orbit of Venus is within ours, and as it jour- 
neys about the sun, within the path that our earth 
describes, it comes between us and the sun, and 
then its dark part is toward us, and its illuminated 
face is toward the sun. When it is to the right or 
left of the sun it presents, according to its position, 
but a half or a quarter of illuminated surface. 
When at last it moves around to the other side of 
the sun it shows us its whole shining disc. Galileo 
first observed these phases in September, 1610. Such 
are rare, glad moments in an astronomer's life. 

If Venus is between us and the sun, why do we 
not have an eclipse of the sun from Venus as we do 
from the moon ? However, in these affairs of the skies 
distance is as important a factor as nearness. We 
have no eclipses of Venus. Venus is so distant and 
so small that it could never have sufficiently great 
apparent size to obscure the sun's disc. Owing to the 
nearness of the moon to us its apparent disc is as 



142 Bstronomg 

great as that of the sun. The passing of Venus between 
us and the sun, across the sun's face apparently, can- 
not occasion an eclipse or hiding. It is called instead 
a transit or crossing. The small, dark body of the 
planet travels across the sun's disc, and in this prog- 
ress has been eagerly studied through telescopes. 
This is a most interesting spectacle, but we may not 
propose it for immediate observation. We would 
need to watch a long while. There will be no tran- 
sit of Venus until 2004. The last one was in 1882. 

If the planet is moving along between us and the 
sun why is there not a transit every year ? 

The time of the planets is different. Venus and 
the earth do not move side by side, like a pair of 
horses in harness ; rather like two racers on a course, 
one with a larger circuit, or greater swiftness, than 
the other. Venus makes thirteen journeys w T hile 
the earth makes eight. Making these journeys the 
earth overtakes Venus once in nineteen months. In 
that case why is it we may not have a transit that 
often ? 

Owing to the inclination of Venus to the plane of 
the earth, in half its journey Venus is above 
our orbit and in half below it, and thus it usually 
happens that when our earth " catches up " with her 
brisk neighbor, Venus is above or below the face of 
the sun, as it appears to us. When one transit has 



liClbite Uenus 



143 



been made, in eight years there will surely be 
another, and then not one for perhaps over a hun- 
dred years. 

We must not think of planet tracks as ring within 
ring, but as of loops of cord, lying not exactly true 
to each other, as if we drop the cord in this wise : 




NOT THIS WAY 



THIS WAY 



How large is Venus ? 

Its diameter is only two hundred and fifty miles 
less than that of the earth. Venus is less heavy 
than the earth, being three-quarters of the earth's 
weight. 

Venus in not only a beautiful object in the skies, 
but its transits have afforded us a scale of measure- 
ments for the other bodies of our system, also one 
very good way of determining the distance of the 
sun from the earth. 

Venus has an atmosphere ; we do not know how 



144 BsttonomE 

deep that atmosphere is, or of exactly what gases it 
is composed. There is evidently moisture upon the 
planet, in lakes, rivers, or seas, for there are clouds in 
its atmosphere, often beautifully colored, as in our sky. 

So far as is known Venus has no moon. Astrono- 
mers have thought they discovered one satellite 
lingering near the beautiful star, but there is yet no 
certainty about it. Though Venus is nearer to us 
than Mars is, it is not so easy of observation, owing 
to its being sunward of us. 

Now we have remained on the hill until all the 
colors of the sunset have faded out of the west, and 
Venus hangs low, close down by the horizon's rim. 
The dews are falling, and the whippoorwills are call- 
ing from the woods. So large, fair, clear is Venus that 
we might fancy our earth had in her a second and 
very small moon. 

As we watch these heavenly bodies it is interest- 
ing to consider how life upon them must be attended 
by conditions very different from anything which we 
know in our world. 

There is little likelihood that man could exist on 
any other orb than his own in our system ; the 
earth has been prepared for him and man for the 
earth. The atmosphere surrounding our world se- 
cures for us a suitable temperature ; the period of 
rotation upon its axis secures for the earth the change 



Mbite Denus 145 

from day to night which man needs for rest and 
quiet ; the period of the earth in its orbit gives us 
the seasonal changes. In our system there are 
globes of fluid or gaseous fire as the sun, Uranus, 
Neptune ; there are frozen globes such as our moon, 
with its day a fortnight long ; there are globes of tre- 
mendous conflict and storm, such as Jupiter, which 
also has a day and night of five hours each, and a 
year twelve times as long as ours. 

Some astronomers consider that Mars is the one 
planet where life conditions are so similar to those 
of our world that, while people constituted exactly 
like human beings could not survive if transplanted 
there, it is yet easy to conceive of beings with some- 
what modified human conditions having there a 
home. Mars has day, night, seasons, atmosphere, and 
probably water; some types of animal life might 
surely be so constituted as to thrive there. 

But how about life on Venus ? Why should not 
the beautiful planet be a fit home for beings so 
nearly like ourselves that we might claim them as 
kin ? The size of Venus is nearly that of the earth, 
being but two hundred and fifty miles less in diam- 
eter ; its density is three-fourths that of the earth, 
and therefore the attraction of gravity is one-fourth 
less. We illustrate by saying that any body that 
here weighed one hundred pounds would there weigh 
10 



146 Bstronomg 

but seventy-five ; a force that would enable one to 
jump forty inches up here would carry one fifty 
inches on Venus ; a body let fall here moves sixteen 
feet in a second, on Venus it would move about 
thirteen. 

While the time of the rotation of Venus is not 
absolutely fixed, it is supposed to be about forty 
minutes less than that of the earth ; thus the happy 
interchange of day and night is assured there as here. 
The climate of Venus would be very much hotter 
than we experience in our world; yet, as in the 
small circuit of our globe we find the luxuriant 
vegetation of the tropics born in seething, moist heat, 
and the small lichen vegetation of the far North, 
thriving on and under beds of snow ; when we find 
man close to the poles, journeying in sledges, and 
dressed in furs, and running nearly naked in equato- 
rial forests, we see that animal and vegetable life can 
support and adapt itself to singular extremes of heat 
and cold. We then consider that plants and animals 
may be fitted for the hotter year of Venus, which is, 
at least, less violent than ours in its seasonal changes. 
Water and an atmosphere Venus certainly has; if 
oxygen is present in that atmosphere there may be 
on the planet life largely like our own. 

Leaving speculations and returning to facts about 
Venus, we find that Venus shares one peculiarity of 



OTbite Denus 147 

the moon in being visible sometimes to the naked 
eye in daylight. As has been said about the moon, 
the white splendor of the planet is so great that it 
often seems as if it must be giving out an effulgence 
of its own, and yet really it is a dark body, such as the 
earth or the moon, splendid only in the radiance it 
gathers from the sun and reflects from its inert sur- 
face. We may take the method before used with the 
light of the moon, comparing the light of Venus in 
daytime with the kind of light shown by brilliantly 
lit clouds, and we see it is all reflected, not self-given. 

The nearness of Venus causes it to be from forty 
to sixty times brighter than any orb in the northern 
sky, and so bright that it can be seen sometimes, as 
the moon is seen, shining in high heaven, and boldly 
challenging comparison with the light of day. 

One might long and pleasantly continue discussion 
of the questions and discoveries which cluster about 
this beautiful planet, which has had so much time 
and labor devoted to its phenomena. The planet 
has been to us a fruitful source of information, it has 
been as a golden measuring-rod whereby we have 
tested the distances and learned the unspeakable 
majesty of the solar system. 



CHAPTER XV 

THE SUN'S YOUNGEST CHILD 

" Yet 'neath a curtain of translucent dew, 

Bathed in the rays of the great setting flame, 
Hesperus, with the hosts of heaven came." 

Why are we not all content to live our own lives 
down here and let questions about the solar system 
rest? 

In all these studies in Natural Science it is that 
we Ci think God's thoughts after Him." That ennobles 
and enlarges the mind, and to these thoughts and 
studies the normal mind is usually drawn. 

What thought are we going to think after our 
little study of the white star Venus ? 

What we might call a hidden thought, Mercury, 
so far as we know, the youngest of the solar family, 
the little child planet, set close by its father's side. 
Long ago the ancient star-gazers discovered, near to 
the setting sun, seen only when the horizon was 
clear of clouds or mist, a small pale-pink planet, 
which they named Mercury, after the god of thieves, 
saying that this star rose to show the thieves when 
to begin their work ! Those old astronomers also 
148 



Gbe Sun's tyounQeet CbilD 149 

saw close to the rising sun, when the morning was 
fair, a small pale-pink star with a clear beam. This 
star they named Apollo, after the god of day. 

Really these two stars were but one ; the planet 
nearest the sun appearing sometimes as a morning 
and sometimes as an evening star. It w r as only after 
many centuries that it w r as fully ascertained that 
what had been called two stars w r as merely one, and 
for that one the name Mercury was retained. Ever 
since that time this lonely little planet oscillating 
about the sun has been an object of curious interest. 

Mercury shines very brilliantly sometimes when 
everything is favorable to its appearance. It is 
about one-fourth as large in diameter as our globe, 
but less than one-twentieth of the earth's weight, 
and is a little over one-third as far from the sun as 
we are. Our orbit is some ninety-two millions of 
miles and the orbit of Mercury thirty-five millions 
of miles away from the fountain of light and heat. 

This little planet rotates upon its axis once in 
twenty-four and one-quarter hours, so its day is about 
the length of one on earth. It completes its short 
orbit in eighty-eight days. 

The mass of Mercury is not quite one-fifth that of 
the earth, but the planet is three times as dense or 
solid as ours is. Upon this compact little globe the 
sun pours nearly seven times the light and heat 



150 BetronomE 

that is afforded to us. A French fable says that all 
the inhabitants of Mercury are mad — that is, crazy — 
because of sunstroke ! We might fancy that the 
planet itself was mad from overheat, it shows so 
much eccentricity in its orbit. As Mercury shows 
the most eccentricity in orbit and Venus the least, 
we may look on Mercury as the spoiled youngling 
of the family of the sun and Venus a3 the model 
child. Eccentricity in orbit means variation from 
the circle. By so much as a planet's track varies 
from a true circle by so much it is eccentric. Mer- 
cury is the most eccentric of the planets, unless we 
except one or two asteroids, which are supposed to 
be very eccentric in their travels. 

If a planet revolved about the sun in a true circle, 
then at all periods of its year it would receive equal 
light and heat. The circle being flattened to an 
ellipse, by just so much as it is in one part flattened 
or pressed toward the sun, the other parts are ex- 
tended or drawn from the sun. As this is a matter 
of perhaps millions of miles, in what is so great as a 
planet's orbit, a perceptible difference is made in 
the amount of heat received. 

Mercury, revolving about the sun, reveals to us 
phases as Venus does. Sometimes Mercury is dark 
to us, the sun illuminating the side that turns from 
us sunward. As it moves to right or left of the sun 



Gbe Sun'a ioun^eet CbflD 151 

we get a half, or quarter, or eighth of the planet 
illuminated, and finally it smiles to us, in full light, 
on the other side of the sun. Of course these phases 
can be seen only through a telescope. Admirably 
delicate as is the human eye it is yet too coarse an 
instrument to detect such fine points as these. The 
object cast on the retina is too small for it to grasp. 
As is the case with Venus, some observers think 
that they have discovered very high mountains jut- 
ting from the crescent Mercury, but this is disputed 
by others. 

When can we see Mercury best, as it lies so near 
the sun ? If the weather is clear at morning and 
evening we can see Mercury in March and April, and 
again in August and September, Look for the star 
in the early twilight, morning and evening. Get 
your planetarium, that will point it out exactly. 
So far as we know Mercury has no satellite. The 
sun is his nearest companion and in the glory of the 
sun he is usually lost to mortal eyes. 

Some think that Mercury has an atmosphere, much 
more dense than ours, but nearness to the sun makes 
the planet so difficult to observe that much about it 
is conjectured rather than proven. 

Have we ever stopped to think that the speed of 
every planet differs in different points of its orbit ? 
At the points in its orbit nearest the sun the planet 



152 Bsttoncmg 

whirls forward swiftly ; farther away it slackens its 
pace somewhat. The planet, like a horse, weary in 
the length of its journey, falls into a walk, having 
gone far from home, but picks up spirit and moves 
briskly again when home is once more in view. The 
reason of change in velocity in the movement of the 
planet is the attraction of the sun ; of course, greatest 
when the planet sweeps nearest. 

We should find living hard work on a planet six 
times hotter than our earth, we think, when wilting 
in summer heat. Mercury must be at least nine 
times hotter than our earth. Its density may cause 
it to receive, store up, and radiate much more heat 
than our globe. Take, for instance, a pound of cot- 
ton and a pound of iron and heat them before the 
fire. The cotton — unless it takes fire and burns up 
— cannot absorb much heat on account of its loose 
texture, and will never feel more than warm to your 
hand. The iron will absorb a deal of heat, because 
its texture is so compact. It will not only burn your 
hand if you touch it, but will make it very warm if 
you merely hold it near. 

Similarly, the surface of the dense planet Mercury 
receives and radiates much heat. The climate of a 
globe does not depend entirely upon sun-heat ; 
atmosphere modifies it. The atmosphere about a 
globe may repel or retain much of the sun's heat. 



XLbc Sun's Youngest CbllD 153 

Knowing so little of the atmosphere of Mercury, we 
cannot be sure of its climate. 

Mercury makes its transit across the sun, affording 
opportunity of careful study. During this transit a 
shadowy circle about the dark body of the planet 
seems to suggest a dense atmosphere. 

It has been thought that the eccentricity of Mer- 
cury in its orbit might be due to some other planet, 
not yet discovered, lying between Mercury and the 
sun. Such a planet has been searched for under the 
name of Vulcan, the god of fires. This interior 
planet has not yet been seen. If it really does exist 
it cannot fail at some time to come in line between 
the earth and the sun, and then will be seen making 
its transit across the glowing face of the sun. That 
will prove that Mercury has a smaller and younger 
brother. Some astronomers think that Venus and 
Mercury rotate only once in their trip around the 
sun. That, however, is not proven. 

There are some countries in the world where the 
planet Mercury is seldom or never seen, and this is 
not owing to their position, but to the dampness of 
their atmosphere causing hazy or cloudy sunsets and 
sunrises. The famous astronomer Copernicus knew 
of the planet Mercury, and greatly longed to see it, 
but died without getting a view of the very planet 
which was the most striking example of those 



154 astronomy 

celestial motions which Copernicus first clearly ex- 
pounded. The vapors in the atmosphere about 
Frauenburg, the home of Copernicus on the Vistula, 
always prevented the eager astronomer from seeing 
the antic little planet. An astronomer so situated in 
these days would promptly step aboard an express 
train or a steamship and visit an observatory in 
some more favorable locality. Traveling was slow, 
dangerous, difficult, and costly in the days of Coper- 
nicus, and he had to give up viewing Mercury, until, 
as Galileo said, " he passed it in his flight among 
the stars after leaving this world, and then knew 
what was true." 

Mercury was doubtless a less easy matter of dis- 
covery than other planets known to the ancient 
world. It seemed, as we have said, not one but two 
planets, and all conditions for observation must be 
exceedingly favorable, or it could not be seen at all. 
Again, none of the planets is so variable in appear- 
ance as Mercury when at last it does happen to be 
visible. Both its height above the horizon and its 
brilliancy vary greatly, so that it seems not possible 
that such different appearances should belong to 
one planet. How many ages, and how many thou- 
sands of observations must have been required to 
establish the fact that these double appositions, these 
revealings of a morning and evening star, of a brill- 



Ma.rs 



/ 



X 



s 



\ 



~~ ^^ Moon, 



/ 



/ 



/ / 









J 



\ 



\ 



\ 



\ 



8 8cT<2.ys. 



/ 



x 



•* 



/ 



^#7 rtciys. 
THE FOUR YOUNGER CHILDREN 



Gbe Sun's youngest Gbilfc 155 

iant and a pale orb were one and the same ; that one 
of these close dwellers by the sun was never seen 
until the other had gone, that both were never in 
the field of vision at the same time, while they occu- 
pied nearly the same place. Learning that Mercury 
was not two, but one, seems a brilliant astronomical 
discovery. 

In the British Islands, Mercury can usually be seen 
during the course of the year ; in the United States, 
owing to the dryer, clearer atmosphere he is freely 
observed, but in the clear skies of the desert of 
Arabia or Africa, must have lived the star-gazers 
who were able to trace the wanderings of this sun- 
child and name him long ago. 

Mercury, being such an intractable little planet 
with which to make acquaintance, we were obliged 
to apply to a comet to learn his mass. How was 
that ? It was early known that Mercury was much 
less in size than our earth, and was also much more 
dense. Of late a new estimate both of the size and 
density of the planet has been reached, which the 
astronomer C. A Young considers more likely to be 
trustworthy than those previously fixed upon and 
given in most books. In the year 1895, when Encke's 
comet was making its flight in our system, between 
us and the sun, it passed, as is its wont, very near to 
Mercury. Xo other sky wanderer, no heavenly orb, 



156 Betronoms 

ever gets so near to Mercury as Encke's comet. Now 
Encke's comet is less active than other comets, and 
is almost structureless, it seems of very tenuous 
material, "like a smoke wreath." Upon, this comet 
the compact little planet Mercury exercises much 
influence, and by the perturbations which it creates 
in the comet, the learned can estimate the mass of 
Mercury. As a consequence of observations and cal- 
culations made in 1895, Backhand, the astronomer, 
and others, conclude that the mass of Mercury is 
only one-thirtieth that of the earth, and its density 
about two-thirds. This shows us that Mercury is 
very much more solid and compact than our earth, 
and if it were as large as our earth its attraction of 
gravitation would be immense, probably twenty times 
as great. 

If the usual question of fitness for habitation 
comes up concerning Mercury, we can only say that 
no beings of which we could form any conception 
could abide there. Dwellers on Mercury would need 
to be those whose native element was something 
very like fire, for upon Mercury the solar heat 
streams forth as upon no other planet of our system. 



CHAPTER XVI 

ECLIPSES AND WHAT THEY TELL 

"Or from behind the moon, 
In dim eclipse, disastrous twilight sheds 
On half the nations, and with fear of change, 
Perplexes monarchs." 

The " Columbian year " was rife with tales about 
the great discoverer, and one which especially charmed 
many children ran about an eclipse, in this wise : 
" In 1502, when Columbus was at San Domingo, 
the natives would not allow his men to land to get 
water, and would not furnish him with provisions. 
He knew that he must have supplies, and he fright- 
ened the natives by telling them that the Sky Spirit 
was angry with them because of their inhospitality, 
and would take away the moon that night. This as 
he knew that there was to be an eclipse. When the 
people saw the moon disappear they were terrified, 
and gave Columbus whatever he wanted." Fiction 
abounds in the use of similar incidents as part of 
the machinery of tales. All ignorant and savage 
people have feared eclipses. They supposed them 
to be signs of the wrath of the gods, and to foretell 

157 



158 Betronom^ 

great disasters. As the theory of eclipses became 
plain, it was found that they could be calculated not 
merely a month, or a few years in advance, but many 
years — even centuries. If you wish to know when 
there will be an eclipse, we say, as Bottom said in 
Shakespeare's " Midsummer Night's Dream": "A 
calendar ! a calendar ! Look at the almanac. Find 
out moonshine ! find out moonshine !" 

However often eclipses occur, they never fall 
into the category of the commonplace. There are 
solar and lunar eclipses. The highest number pos- 
sible in one year is seven ; the lowest is two. When 
there are seven, five will be sun eclipses, and two of 
the moon. If there are but two, both will be solar. 
The usual number in a year is four. We have noted 
in a previous chapter that an eclipse of the sun was 
caused by the coming of the moon between the earth 
and the sun, so shutting out the light of the sun from 
us. An eclipse of the moon is caused by the moon 
being in opposition — that is, on the side of the earth 
opposite the sun, and so receiving its full rays, and 
our earth cutting off that light by coming between 
the sun and moon, and casting her shadow upon the 
moon. 

An eclipse may be total, or partial. An eclipse of 
the sun must always occur when the moon is " new ;" 
an eclipse of the moon can only take place when the 



jEcltpeee and Wbat Zhev Cell 159 

moon is " full." The reason for this is, that the 
moon never comes between the earth and the sun to 
afford an eclipse except at the period called " new 
moon ;" and she is never in opposition to be eclipsed 
herself except when at the period of "full moon." 
In the total or partial shutting out of light, called an 
eclipse, the sun is darkened by the moon, the moon 
by the earth. 

To make the theory of eclipses plainer, let us talk 
a little about shadows. When light is thrown upon 
any opaque body, that body casts a shadow. Every 
planet, big or little, casts a shadow in the direction 
opposite to the sun. The form and size of these 
shadows depend upon the comparative size of the sun 
and the planet, and their relative distance. For a 
practical example, let us take some oranges, and let 
us illustrate the law of shadows. Here are two 
oranges of equal size. Let one represent the sun 
shining upon the other one; half of the one is lit 
up, its other half lies in shadow, and that shadow 
will fall in the shape of a cylinder. If there were 
a planet equal in size to the sun — which there is not 
— the shadow cast into space by that planet on its 
night side would be cylindrical. 

Take away the orange that we called a planet, and 
choose a small one. The shadow cast by the small 
body, illuminated upon one side by the sun, is not 



160 BstvonomE 

a cylinder, but a cone. The shadow tapers off 
until it ceases altogether. If the planet were greater 
than the sun, the shadow w T ould not be cylinder- 
form, it would not diminish as a cone, it would 
expand. The nearer the sun to the great planet 
it illuminated the more widely the lines of shadow 
would diverge. 

As all the planets are smaller than the sun, each 
casts a cone-shaped shadow. 

If the moon's orbit, or path, lay exactly in the 
plane of the ecliptic, the moon would eclipse the sun 
every month. Just here we might explain what is 
meant by the frequently used phrase, " the plane of 
the ecliptic ?" 

The ecliptic is a vast imaginary circle drawn in 
space, having the sun for its centre. Every part of 
this circle lies true, or level, to the centre of the sun. 
Imagine this great sun-centred circle ; now fancy 
that you can lay a long ruler upon the lower edge 
of the ecliptic, or circle, and push it steadily forward 
until it passes through the sun's centre, and then 
on, and finally off the upper edge of the circle, the 
ruler lying true to the circle all the time, and in its 
progress touching every part of it. That is the idea 
of the plane of the ecliptic; or, fancy a sun floating 
half buried in water, and let the water surface be 
the plane. 



JEclipses anD Wbat Zhev Zcll 



161 



If the orbit of the moon were true to this plane 
the moon would pass before the sun each month, 
and cast her shadow upon the earth, so that we 
should lie in her shadow and see her dark form 
against the sun, shutting out our light. The moon's 
orbit is, however, tilted about five degrees from the 
plane of the ecliptic, and therefore at new moon she 
may be between us and the sun, or she may be above 
or below the line. Also at full moon she may be 
above or below the line again, and so not be eclipsed 
herself by the shadow of our earth. Thus : 





Belc 



An eclipse of the sun comes on from the west- 
ward, the shadow moving across from the sun east- 
ward. In an eclipse of the moon the shadow falls 
upon the moon on her eastern side, and moves over 
11 



162 BstrononiE 

to the west. This is because of the eastward motion 
of the moon in her orbit. 

How long is the cone of shadow which our earth 
casts ? 

About eight hundred and sixty thousand miles ; 
more than three times the distance from the earth 
to the moon. The average breadth is some six 
thousand miles. It is wider close by the earth, and 
narrower farther along. When it reaches the moon, 
its breadth is about six thousand miles — that is, 
three times the diameter of the moon. Plenty of 
room to lose the moon in that shadow ! 

The length of the moon's cone of shadow averages 
two hundred and thirty-nine thousand miles ; it 
varies between less than that and more than that, 
according to the moon's distance from the sun. As 
the moon's orbit is elliptical, and the earth's is also, 
she is at some periods nearer the sun than at others, 
and her shadow cone changes its length with the 
distance. Sometimes it is two hundred and fifty-two 
thousand six hundred and thirty-eight miles, or 
more than twelve thousand miles longer than the 
distance between the earth and the moon. Its 
breadth at the distance of the earth is only one hun- 
dred and seventy miles. The lighter extent of shadow 
beyond the very dark portion is, however, sometimes 
over four thousand miles in width, 



jecliveee and TJMbat Gbes Gell 163 

The dark shadow of an opaque body is called the 
umbra, a Latin word, meaning a shadow. All por- 
tions of a shadow are not alike dense ; on each outer 
edge of the shadow there is a portion of lighter 
shadow, called a penumbra. 

A partial eclipse of sun or moon is when the inter- 
vening body passes over but part of the eclipsed 
disc. When the earth's shadow falls centrally upon 
the moon, the moon is always totally eclipsed. An 
eclipse of the sun is central when the moon's shadow 
falls full on the sun's centre ; it will be total if the 
moon is so placed in regard to the earth that her disc 
is apparently as large as that of the sun. If her 
apparent size is less than that of the sun, the eclipse 
will be annular, a ring of the sun's glowing disc 
showing all around the moon's shadow. 

While an eclipse of the moon can of course be 
watched by the naked eye, and the general public 
frequently views a solar eclipse with great satisfac- 
tion through a sheet of smoked glass, it is in observa- 
tories that the eclipse awakens an intense . interest, 
and in them all are at work to learn what they may 
from this " revealing by hiding." 

For some years past there has been a revival of 
interest in the subject of astronomy, and an unusual 
activity in the building of observatories. As we saw 
in the case of Camille Flammarion and his observa- 



164 Bstronoms 

tory, the wealthy amateur often comes to the aid of 
the learned astronomer, providing him with the 
requisite tower or instruments, while colleges are 
now demanding a far better apparatus than once 
would have contented them. 

Telescopes are now constructed with lenses of 
such immense size as once would have been esteemed 
a wild dream. Nations or individuals are choosing 
sites which would be particularly favorable for star 
study, and there providing an astronomical equip- 
ment adequate to the desired end. Thus Arequipa 
in South America has an observatory which enjoys a 
peculiarly clear atmosphere on its Andean elevation, 
and Arizona, in our own country, has an observatory 
as a station auxiliary to Cambridge, as in Arizona 
the dryness of the air permits of work which may 
be hindered in other places. Greenwich and Mendon 
in Europe have now telescopes of the largest size, 
and the Mendon observatory has an adjunct on the 
frowning and silent slopes of Mont Blanc, where, on 
special occasions, astronomers may resort for special 
work. American astronomers, aided by men of 
wealth, are working in the Arequipa observatory in 
Peru, and the principal telescope there has a lens 
with a diameter of eighteen inches. We are told 
that the work in Peru will be of a kind that cannot 
be done in Cambridge, because there the sky is all 




A TOTAL ECLIPSE 



Eclipses an<> TLClbat Zhc\: Cell 165 

night long illuminated by electric lights. From this 
Ave see that the luxuries of an advanced civilization 
have their peculiar disadvantages. The " new as- 
tronomy," as it is called, requires for its observations 
a pure atmosphere and a sky free of the glare of 
reflected city lights, or the outpouring of city smoke. 
Italy has always been a land of astronomers, we 
might say of astronomers working under difficulties. 
for during long ages neither the Church nor the State 
aided or abetted astronomical studies. Galileo's name, 
of course stands first among the Italian star lovers ; 
Cassini, Piazzi. and others range near him. Pisa fur- 
nished the world with a telescope ; Schiaperelli, Padre 
Denza, Padre Sais. and others are now doing a grand 
work and have been accorded grand opportunities. 
The observatory of the Vatican is associated in all 
minds with the revision, under Gregory XIII. of the 
calendar. The tower of this structure is called the 
Gregorian Tower, a massive domed building having 
twenty rooms, where all manner of astronomical work 
is carried on. After the calendar was revised, and the 
enthusiastic worker, Ignazio Dante, and his assistants 
were dead, the Vatican observatory fell into neglect, 
the instruments were not renewed, many were in- 
jured or lost, dust gathered on the floors and 
windows, and spider webs hung thickly upon the 
walls. Now. while a line of spider's web is invalu- 



166 Hstronomg 

able in some observations, draperies of spiders' webs 
in observatories suggest that enthusiasm in astronomy 
has sunk to its lowest ebb. In 1888 the Vatican ob- 
servatory was remodeled and refitted, given a good 
endowment, learned and zealous men were called to 
it, an ancient tower, the Leonine, was added to the 
observatory and thoroughly equipped. This tower 
is said to be almost as solid as the Pyramid of 
Cheops, and was originally built as a fortress against 
Saracenic invasions. Owing to its massive solidity 
and position on the Vatican hill, this tower is nearly 
free from vibrations which interfere with so many 
observations. Here a very great work has been done in 
photographing the heavens ; cloud photographs have 
also been taken in large numbers, and various series 
of valuable photographs of eclipses — both lunar and 
solar — have been made. 



CHAPTER XVII 

THE STORY OF THE TIDES 

"The tide rises : the tide falls : 
The twilight darkens, the curlew calls ; 
The little waves with their soft white hands 
Efface the footprints in the sands : 
The tide rises : the tide falls." 

Reference has frequently been made in these 
pages to an instrument called the spectroscope. 
Chemistry brought this instrument to the aid of 
astronomy. Chemistry is the study of matter, as 
composed of atoms ; and the study also of the atoms. 
The chemist analyzes, or divides up, substances, to 
discover of what they are composed. When a 
substance can no longer be divided, it is called 
simple. 

Air was analyzed and found to be composed 
chiefly of oxygen and nitrogen, and these gases 
were called simple substances. In the course of 
research and improvements in chemical work it 
has been found that substances once supposed to be 
simple can be still further divided into two or more 
compounds. It is hard to say what is really simple ; 

167 



168 Betronomtf 

« 

what we call simple this year may be proved capable 
of division next year. 

Chemistry gave us the spectroscope, and chem- 
istry has applied this wonderful instrument to sun 
study. What is called the solar spectrum is an 
image of the sun cast in lines arranged according to 
what is called wave-length. This divides light into 
the various colors of which it is composed, and the 
colors tell us in various darkened lines what sub- 
stance has cast them. 

It was found that some substances seemed to be 
in the sun which had not elsewhere been discovered. 
One was named helium, or " sun-stuff." 

Astronomers said if the theory that the various 
planets were formed from the sun were true, then sub- 
stances found in the sun should more or less pervade 
the planets. They set about a diligent search, and 
found helium in meteoric stones, and also in this 
world. This gave fresh confirmation to the nebular 
theory, the theory which asserts that all our solar 
system was once embraced in the sun. 

The spectroscope has assured us of the gaseous 
nature of the sun, and also of its capacity for con- 
tinued heat-giving. Sir Robert Ball gives us a very 
fine illustration of this. He says that the sun is a 
vast ball of enormously heated gas, and contraction 
is as a hand constantly squeezing that ball. As a 



Zhc Ston? of tbe Zibee 169 

sponge full of water pours forth water when squeezed, 
so contraction squeezes heat from the sun. This 
contraction, or squeezing, constantly lessens the 
diameter of the sun. The lessening is at the rate of 
ten inches each day. So great is the size of the sun 
that this shrinkage can go on for thousands of years, 
without causing any noticeable difference in size or 
heat, except when measurement is applied. 

This consideration of the gaseous nature and fierce 
activity of the sun suggests to us the theory of tides 
in the sun and tides in all the planetary bodies cast 
off from his substance. Let us study for a little, 
tides as known in this world. 

The tides are the daily pulse-beats of the sea. 
Every one who visits the coast has noticed that twice 
each day of twenty-four hours the waters rise high, 
and creep up on the beach. Twice each day the sea 
shrinks and withdraws, and leaves the sands bare, 
far away. We understand that these tides are 
caused by the moon. This has been known for 
hundreds of years. 

Long ago there must have been the first man, or 
first few men, who thought out for themselves this 
connection between the tides and the moon. We 
do not know who these men w T ere, but we are sure 
that they were deep, earnest thinkers, and careful 
observers to discover all this, unaided by instruments 



170 BsttononiE 

or any knowledge of the great law of the attrac- 
tion of gravitation ; all that we can say about them 
with certainty is, they must have been people who 
lived by the sea, and saw its changes every day ; 
they were those to whom the tides meant something 
personal ; they were surely sailors, fishers, or mer- 
chants who traveled upon ships to do their trading. 

Not only are there two daily tides, flowing and 
ebbing in regular periods, but the high tides have a 
period of being very high, and the low tides of being 
very low. The very high rise is called a spring tide ; 
the very low ebb is named a neap tide. 

The attraction of the moon is the chief cause of 
the tides upon our globe. The sun has also tidal 
influence, but the sun is so far from us that his 
attraction is less noticeable. When the attraction of 
sun and moon combine, that causes the spring tide. 

Tides out in mid-ocean are less marked than on 
continental shores. The island of St. Helena has 
very low tides. Bodies of water nearly inclosed, as 
the Mediterranean and some other seas, have very low 
tides, almost none in fact. 

Tides set far back in rivers and inlets ; they are 
noted perhaps a hundred miles inland. At some 
places the tides rise very high ; they press up the 
Thames to a depth of eighteen or nineteen feet at 
London. In the British Channel the tidal waters 



Zhc 5tot£ of tbe Zibes 171 

crowd up, swelling against the cliff, so that spring 
tides rise thirty-eight feet, and neap tides are but ten 
feet lower. 

The highest of all tides are noted in the Bay of 
Fundy, where the rise and fall of a spring tide is fifty 
feet. This mass of water, gathering in from the open 
sea, comes with a great sudden swell or bore. There 
is a distant, deep, warning sound, as the roll of thun- 
der in a heavy storm. The hogs, which go down to 
the beach to feed on mussels, oysters, and crabs, lift 
their snouts from rooting in the mud, and gaze 
earnestly seaward. Then they jerk up their heads 
high with a " woof! woof! woof !" and away they go, 
pell-mell, as fast as they can race inland, until they 
are well out of the way of the advancing water. 

The rise and fall of the tides causes strong cur- 
rents ; these can be used, as any other water power, 
to drive machinery. 

Tides have cut down banks and carried away large 
tracts of country. On the other hand, tides have 
brought material and formed banks and new levels. 
Tides have had much to do with carving the out- 
lines of the land, cutting out inlets, bays and straits. 
Far out at sea the tides cause currents which are 
very useful to navigators. 

There is one very interesting fact which we may 
not at first blush be able to understand — this is, that 



172 Bstrcmom^ 

the tides draw upon and lessen the stock of energy 
in our earth. As this is lessened, the earth rotates 
more slowly upon its axis, and thus the day is 
lengthened.* This process is so slow that many 
thousands of years must pass before any visible 
difference would be made. 

Tidal influence reacts upon the moon, and has 
driven the moon farther from the earth since her 
formation. No doubt this retreating of the moon 
may still go on to some slight degree, but the present 
distance will not be appreciably changed for many 
ages. 

The creating of tides upon one planet by the 
attraction of some other planet extends through all 
the solar system. Many of the planets have not yet 
reached a stage where there is any water upon them, 
but water is not necessary to tidal motion. Tides 
can be created in a body that is all of heated gas, or 
is in a fluid or semi-fluid condition of molten mate- 
rial. Tides can be also in the interior of a planet, 
which has a fluid core under a hardened or solid 
crust. If you had a hollow ball, and filled it with 
thick syrup, when you spun the ball over you would 

*This exhaustion of energy by tides may account for the 
slow rotation of the moon, making one moon day a month 
long. 



ftbe Stots of tbe aides 173 

create motion in the syrup. When the force in 
question is attraction extended over the body with 
the soft interior, tides are created. The force of 
tidal ebb and flow acts upon the planets in their 
motion, hastening or retarding their rotation. 

In speaking of the building of our earth, its change 
from gaseous to a solid crust, and the transforming 
of this crust into continents, islands, seas, much of 
the surface becoming fertile, productive, or arable 
land, we noted that water had been a great earth- 
carver. Water had carved out shores, had chan- 
neled out river beds, had eaten out of straight coast 
lines the curves of bays and gulfs ; water had carried 
sand, loam, alluvium ; water had laid down miles of 
chalk or sandstone rocks. The tides on the earth 
during all these formative ages were busy workers ; 
probably they were' much higher, more masterful 
tides than now. 

This work of water in cutting away or building up 
land still goes on. Those who lose land, house sites, 
by the fury of tidal wash, are likely to speak of tides 
as great robbers ; but on the contrary, they usually 
give as much as they take, building up with one 
hand what they tear down with the other. At Cape 
May Point at very low ebb one often sees over a 
quarter of a mile beyond present water-mark the 
traces of wells and houses which were once upon the 



174 Bstronomg 

shore, with a considerable strip of land between 
them and the level of high tide. Now the land 
which they occupied is all under water and sea sand, 
while the coast line is nearly half a mile farther 
inland. At Atlantic City the same thing has occurred, 
though there is land there which has been captured 
and returned by the sea several times. 

Some one has made the calculation that the gnaw- 
ing and wash of tides will completely eat up the 
British Isles in the course of five billions of years. 
What will happen at a date so remote is probably of 
very little consequence to any one now living in 
England. 

On the other hand the rivers seem to be combat- 
ing with the tides, the tide's overflow, rendering 
salt and to a large degree worthless, much low-lying 
land at the mouth of great rivers. The rivers bring 
down from the uplands of the interior a very great 
quantity of rich soil, which is deposited on the low- 
lying land near the banks. As much as two or 
three inches of this good earth will be deposited in 
the course of a tide. In about three years seven feet 
of arable soil has been laid down in some localities, 
and the rivers Trent and Ouse, which are famous as 
carriers of solid matter, have built up near the coast 
thirty thousand acres of exceedingly fertile land. 
In our own country the Mississippi carries down 



XLhc 5tor£ of tbe Gifces 175 

from the far Northwest, the headwaters of the Mis- 
souri and other rivers, more than three millions of 
tons of good soil each year, and where this is spread 
about on the line of the Gulf good land appears 
where long ago was only the salt marsh. 

Against this laborious carrying and building of 
the tireless rivers we may set the fury of sudden 
great and terrible tides when sun and moon and 
storms unite their force, swelling over islands and 
sweeping away in a few hours all vegetable and 
animal life, leaving them wastes of bare, tide-borne 
sand, riven, gullied, desolated by the immense fury 
of the waters. 

The rivers, in bringing down the enormous 
amount of earth, leave the interior highlands 
denuded, and as this process goes on inimitably 
we may note that the work of the rivers is trans- 
ferrence merely. What it places in one locality 
it tears away from some higher locality, placing 
the material where the tide may eventually eat it up. 



CHAPTER XVIII 

THE FAR-OFF STARS 

' ' Many a night I saw the Pleiades, rising through the mel- 
low shade, 
Glitter like a stream of fire-flies, tangled in a silver braid." 

How often not only as children, but when of a 
mature growth, w r e have wished for one of those 
wonderful genii told of in the " Arabian Nights," 
bound to do the bidding of him who released the 
genius from under the seal of Solomon. What 
errands there are beyond human accomplishment 
which such spirit could perform for us ! How fre- 
quently, on starry nights, when we are ravished by 
the splendors of " the vault studded w T ith inextin- 
guishable fire," we have wished for a messenger to 
send to the far-off stars. Now we are fortunate, for 
not only has one afrite been on such an errand, but 
three have reported their discoveries. 

What are the names of these wonderful servants 
that have voyaged into space for us ? Afrites Tele- 
scope, Chemistry, Mathematics. Afrite Mathematics 
discovered Neptune and the asteroids. He reports 
that the stars are more distant than we can imagine. 
176 



Zbc Jfat^ott Stars 177 

The numbers which he uses to express their far- 
offness are too great for our comprehension. These 
stars are called fixed stars, because from age to age 
their general position remains the same. Doubtless 
they are all moving swiftly, carrying their systems 
with them, but so great is their distance that only 
careful calculations can detect their change of place. 
We know that ships far out at sea seem motionless 
as we watch, them from the shore, although they 
may be moving a number of miles an hour. 

When we look at these stars they sparkle or 
twinkle. The planets shine upon us with a serene, 
steady light. The fixed stars are light-givers as the 
sun is, not light-receivers, as the planets. 

The size of the stars varies, and for convenience 
in study they have been divided, according to size, 
into twelve classes. Six classes of the largest are 
visible to the naked eye ; the others can be seen 
only by telescope. The reason of this variation in 
size is not always a real difference in the magnitude 
of star and star ; it is often the distance that causes 
apparent difference. 

No doubt there is a real difference in magnitudes, 
as is said in the Bible : " There is one glory of the 
sun ; and another glory of the moon ; and another 
glory of the stars : for one star differeth from another 
star in glory." 
12 



178 Hsttonomfi 

Most of the fixed stars are larger than our sun. 
Sirius is supposed to be as large as eight suns like 
ours. Vega is as large as thirty-eight suns. 

Mathematics has been able to weigh the stars, but 
not to measure them accurately. This magician hints 
that there are nine thousand millions of star-suns 
in space. He reminds us that our sun is a star, and 
that all the light we have is starlight. We talk of 
" moonlight," " sunlight," and " starlight " — it is all 
starlight. Our sun is a star, our moon shines by re- 
flection of that star. 

As to distance, one tries in vain to realize it. The 
nearest fixed star is trillions of miles off. Light 
travels at the rate of one hundred and eighty-five 
thousand miles a second, yet so far off are the stars 
that it takes their light from three and a half to 
many thousand years to reach us. If to-day one 
such star suddenly perished, for a thousand years 
the light that has already left it would be stream- 
ing to us. 

What does the Telescope report to us? He is 
younger than Mathematics ; Mathematics is the 
afrite of certainties of fixed laws. The Telescope 
varies his reports with his growth and his adjust- 
ment. He has made many excursions into space. 
He says that indescribable beauties reward his search. 
He has found out that stars which seem to lie near 



£be jfat^oft Stars 179 

together seem so from their great distance from us, 
and really are far apart. He has had amazing revela- 
tions of size and brightness. 

Herschel was one day looking through his tele- 
scope, when Sirius, a star of the first magnitude, was 
brought into the field of vision. The splendor was 
as the dawn of day ; dazzled by the glory the astron- 
omer was obliged to turn away his eyes, as if he had 
tried to look upon the sun. Sirius is the most 
brilliant of the stars, and is a million times farther 
from us than the sun is. Sirius moves at the rate 
of a thousand miles a minute, and shows variations 
or oscillations that suggested that some large body 
near him must be attracting him strongly. 

After search, this body was discovered by a young 
man named Clark, who, with his father, was trying 
a great glass for the Chicago University. Mr. Clark 
turned his new glass toward Sirius, and cried out, 
" Father, this star has a companion !" Thus the dis- 
turber of Sirius was found. This companion of 
Sirius is seven times heavier than our sun. 

The telescope has learned that some stars are 
variable. Algol, a star of the second magnitude, 
shrinks to a star of the fourth ; then waxes again to 
the second, and so in ceaseless alterations. 

Herschel discovered that there are stars which to 
the unaided eyes appear as single points of light, 



180 asttonomg 

but through the telescope are seen to be double or 
multiple. A list of eighty double stars has been 
published. There are stars which seem to be double 
which may really not be connected, yet there are 
true double or multiple stars, and these vary in 
colors. Mathematics came to our aid to explain 
these double stars. Castor is a double star ; the 
Pole star has a little companion, while our red 
star, Beltegueze, is one of a triple set. 

The telescope afrite found red, blue, white, yellow, 
and green stars. He also reports what are called 
temporary stars — stars that disappear, stars that ap- 
pear where none were seen before. Another discov- 
ery by these two afrites is, that no stars are fixed in 
the sense of being moveless. " Systems revolve 
about systems; suns about suns." The whole 
splendid retinue seems sweeping toward some com- 
mon centre, in the direction of the constellation of 
Hercules, which, thus far, seems to be the centre of 
stellar motion. 

What has Chemistry done for us ? 

Mathematics set off with scales in one hand, and 
a measuring rod in the other. Chemistry took with 
him a prism. His object was to find out of what 
worlds were made. He had a list of gases — he 
weighed, analyzed and compared. He came back 
and hinted that the colors of stars might be accounted 



Cbe jFar=off Stars 181 

for by the stage of development as worlds which 
they had reached ; it is suggested that white stars 
come next after nebulae, and yellow stars are a 
little farther advanced in density ; with red still 
farther on. When Chemistry made that suggestion 
science looked doubtful, and said : " Wait a while and 
investigate before you announce that." 

"At least/' replied Chemiso, " I have found out 
for certain that all these spheres are made of about 
the same material. I have also been assured that 
the sun is not likely to burn itself out ; that there 
are various ways of renewing its energy, restoring 
its heat and light." 

Perhaps we should add to the three afrites already 
mentioned, a fourth, a modern, who may be capable 
of greater and greater achievements. This is the 
Camera. It is only very recently that the camera 
has been set at work in the cause of astronomy, and 
already it has found scores of asteroids, and has 
shown us discs of some of the far-off stars, discs 
which even through the telescope could not be 
grasped by the human retina. 

Of all the six thousand stars which are visible to 
the naked eye, only about one in a hundred show 
any variations, but the camera has shown to us 
clearly the periodic changes of certain beautiful star 
clusters where six or ten in each hundred are vari- 



182 BstronomE 

able. One of these star clusters where numbers of 
orbs are variable is in the constellation of the Hunt- 
ing Dogs, and another in Sirius. These stars having 
been repeatedly photographed, when the negatives 
w r ere compared it was found that the stars varied in 
the photographs. As might be expected, the obser- 
vations and photographic work which detected these 
changes were possible in the observatories in the 
clearest atmosphere, and Arequipa, Peru, is the 
station where the best work of this kind has been 
done. 

These great star clusters are so packed, as we may 
say, with stars that at their centres the star images 
crowd and overlap, this not because they really 
crowd upon each other in their celestial stations, but 
from number and immensity of distance they appear 
to do so, until these groups of stars revolving at vast 
distances each from each, appear on the photographic 
plate or through the finest telescopes to be hazy and 
crowding masses of fire. At such distances no stars 
appear to be of great magnitude ; all are small. Now 
it is found that these stars change, expanding or con- 
tracting their light, so that at one time they may be 
half or double as large again as at other times, or may 
seem to shrink from their usual size. It was for- 
merly supposed that only a very few such variable 
stars existed ; now they are discovered to be numer- 




Ji> n &jj-B*. rh* L 



THE AFRITES OF SCIENCE 



Cbe ffarsoft State 183 

cms. The reason for their changes has not been 
fully ascertained ; several suggestions have been 
made. As all these stars are suns, and are no doubt 
much greater than our sun, it is possible that they 
change in size and light-giving by outbursts of 
chemical activity. Our sun has been known to shoot 
out spires or jets of burning material, which are 
twenty or forty thousands of miles in height, and 
vary several thousands of miles in a few hours. 
Possibly these variable stars have periods of excessive 
combustion, when prominences of such immense 
extent and intense brightness leap up upon their 
entire surface that they increase their magnitude to 
one-half as much, or even double it, and then by the 
transient subsidences of so great activity the apparent 
dimensions are again reduced. To such outbreaks as 
these in the far-off variable stars the excitements or 
corruscations of the surface of our sun are mere 
miniature. Professor Young suggests that an ex- 
planation of some variations of stars can be found 
in eclipses which are taking place when the particu- 
lar star is under observation ; or the intense access 
of light may be due to collisions between the atmos- 
pheres of stars brushing past each other in their 
flight through space ; and this theory is given a cer- 
tain probability by the fact that there are the most 
exhibitions of variation in stars that are near the 



184 BetrcnomE 

centre of clusters where stars are very much crowded. 
No doubt the list of variable stars will be largely- 
increased. Already the period of variation or dis- 
turbance can be predicted in some of these stars, as 
eclipses of the sun or moon can be predicted, but 
according to astronomers the majority of the variables 
are very antic and erratic in their behavior, and no 
one knows when they will " break out." 

Small as is our knowledge of the fixed stars, it is 
yet immensely greater than it was less than a century 
ago, and now makes rapid progress, keeping pace 
with the wonderful improvements in the power and 
precision of telescopes, and with the application of 
new instruments, such as the spectroscope and the 
camera, to the study of astronomy. The achieve- 
ments of the modern astronomy would have seemed 
a fantastic dream to the star-students of Galileo's day. 

Once a telescope for astronomical use was a small 
instrument that could be easily lifted by the hands, 
and having a lens a few inches in diameter; now at 
Mount Hamilton, in California, there is a telescope 
with a length of sixty feet and a lens of thirty-eight 
inches clear diameter; the telescope of the Lick 
Observatory has a lens forty inches in diameter, the 
length of the instrument being sixty feet. Such a 
telescope is mounted on a ponderous pillar, and a 
mechanism so delicately ppised and adjusted that the 



Gbe ffat=off Stars 185 

very slightest movements can be quickly and easily 
made. In some cases the needed movements are given 
by clockwork. 

The telescope of the Earl of Rosse at Parsonstown 
is mounted between two pillars of masonry, and the 
tube of the instrument is so " large that a tall man 
can walk through it without stooping." Yet we need 
not suppose that all the work, or the greatest work 
of astronomy, has been done by means of these 
enormous instruments — the moderate sized tele- 
scopes, which are brought to a great optical perfec- 
tion, have often been used in the most fortunate 
observations. By all these methods of modern 
science, by these instruments of the nineteenth cen- 
tury, we make our harvests of knowledge among 
the far-off stars. 



CHAPTER XIX 

METEORS AND SHOOTING STARS 

" A glittering star is falling 
From its shining home in the air." 

We would do well to be wide awake to-night, for 
there is to be a " meteoric shower ;" probably it will 
begin by nine o'clock, and what are popularly called 
" shooting stars" will be plenty. A bright light 
flashes along the sky and fades, then another, and 
another. Some one cries out in the darkness of the 
chilly November night, " I see a falling star ; one, two, 
three!" — the rain of harmless fire has commenced. 

These are called stars, but are not stars at all ; they 
are meteors. If they are not stars, why do they 
shine? They shine because they are hot, red hot, 
white hot. Why do they go out? Let us discuss 
affairs around and about this question' before we 
answer it directly. Does not a bullet or a cannon 
ball become heated when it is fired from a gun? 
We have picked up bullets that are very warm, just 
after they have been fired at a mark : they have been 
thus much heated, simply by passing swiftly through 
the air for the short space that separated the marks- 
186 



/Ifceteors at^ Shooting Stare 187 

man from the mark. The rubbing or attrition 
against the air heats them. Meteors move so much 
faster and farther than shot or balls that they be- 
come heated incomparably hotter. In the emptiness 
of space they whirl about the sun, each safe in its 
own track, until that track sweeps it into the earth's 
attraction. When, several hundred miles from our 
earth, it enters our atmosphere, friction heats it and 
presently its visibility begins, its destruction may be 
near. Finally many of them are by their intense 
heat expanded into fluid, then into gas, and burst 
into atoms, as an over-blown bubble bursts. When 
they burst we lose sight of them ; we say " they go 
out " or " have fallen to the earth." Millions of them 
are held as fine dust, ever drifting about in the upper 
layers of our atmosphere. Some of them fall upon 
the earth before they lose their condition of stones. 
For a long time these meteors were regarded as a 
fashion of accidents — unexpected, fortuitous happen- 
ings ; but nature has no accidents, all moves by 
steadfast laws. It was finally noted that at certain 
periods of the year these meteors were especially 
numerous, so that they were said to fall in meteoric 
showers. The time of these showers being known, 
it was less difficult to reason of the why of their 
occurrence. 

While the two great shower periods give us an ex- 



188 Bstronom^ 

hibition of the greatest number of meteors there is 
scarcely a night in the year when one or more 
of these bright bodies does not flash in a trail of 
fire across the heavens. These are laggards from 
the one grand army of meteors or scouts sent hurry- 
ing in advance of the other grand army. The inves- 
tigation of these meteors is of much interest. We 
have talked about enormous heavenly bodies. Even 
the smallest of the asteroids and satellites which we 
have spoken of is large in comparison with these 
meteors. Meteors vary in dimensions from many 
tons weight, or many pounds weight, to the size of 
eggs or little pebbles, and some astronomers suggest 
that there are plenty of individual meteors no 
larger than grains of sand. " There are more me- 
teors in space," says one, " than there are fishes in 
the sea." 

Specimens of meteoric stones are to be found in 
most museums. Several weighing over fifty pounds 
are known. In the fall of meteors so large as these, 
trees are known to have been cut down or broken, 
and the stones have been found buried from one to 
three feet in the soil by the force of the fall. 

These meteoric stones are not cold shooting stars 
that have expired upon the earth. The meteoric 
stones have probably a different origin, though ex- 
actly what that is, is yet in doubt. Late as we live 



/Ubctcora and Sbootinfl Stare 189 

in the worlds history there is yet plenty to be 
learned. 

We are told that there are inconceivably many 
meteors, and that they move in great " shoals," as 
they are called. They obey the laws of the solar 
system; the shoals are widely scattered, yet the 
members are held in company by attraction, travel- 
ing in an ellipse about the sun. 

The strongest telescopes cannot discern the indi- 
vidual bodies, until drawn by the attraction of our 
earth they leave their wonted orbit and rush toward 
her surface. Thus entering our atmosphere we call 
them " shooting stars," from their brilliant light and 
swift descent, 

The velocity with which these meteors approach 
us is great, often more than twenty miles a second. 
Xear the surface of the earth our atmosphere is more 
dense, and that high rate of speed cannot be main- 
tained. Far up in space there is no atmosphere to 
hinder their onrush in the direction of any planet 
which has laid hold of them by attraction. 

The entrance of a meteor into our atmosphere is 
like firing a bullet into water. The speed is checked 
by the density of the medium which it enters. Yet 
the speed is still so great that the friction of the 
atmosphere makes the meteor red hot, white hot, 
and finally many of them are so hot that they are 



190 Betronomg 

converted into vapor, and vanish away in invisible 
gases. 

Are we inclined to ask how all that heat can be 
developed by such a small affair as friction ? Fric- 
tion is a very great affair. When just the little fric- 
tion we can arouse by rubbing a knife-blade on a 
piece of cold iron, or rough carpet, will make the 
blade so hot that it will burn one ; when we can rub 
two sticks together until they take fire, we might 
guess what heat would be excited by matter moving 
twenty miles in a second. 

Some shooting stars have left famous records of 
their size and brightness. Some have been seen for 
several seconds by many people scattered over a 
large extent of territory. One seen in England in 
1869 had a long train of light behind it that was 
seen for fifty minutes. This appeared like the tail 
of a comet and was, no doubt, a portion of the 
meteor reduced to burning gas by the heat of friction. 

Various wonderful star showers have been noted 
and recorded in history. These records finally di- 
rected attention to the time of year in which the 
showers occurred, and this led to further investiga- 
tions. During the last one hundred years various 
facts in connection with shooting stars have been 
arrived at. 

There are within the bounds of our solar system 



dfceteots anfc SDootmg Stars 



191 



certain* vast shoals of these small meteoric bodies. 
They are inconceivably numerous and lying from 
one to several miles each from each. A shoal may 
stretch over hundreds of thousands of miles. Each 
shoal of these minute bodies pursues an elliptical 
path about the sun, just as do the separate 
planets. 

On they sweep in their broad track, and if noth- 
ing interfered with their journey they would pursue 




''Meteor 

iov ohosA. 

it again and again for ages. But something does 
interfere. The crowded shoal of little bodies crosses 
the orbit of our earth, and drawn by her attraction 
myriads of meteors desert their ranks and rush to 
her. In November and April, as may be seen by this 
sketch, our earth crosses a meteoric shoal orbit, and 
thus, knowing when the orbits cross, we can predict 
the star shower. There are also, as has been said, 
laggard meteors, drifting behind their train, which 



192 BstronontE 

may be caught by our greedy earth on other 
occasions. 

Several such shoals of meteors are known and 
named. One is called the Leonids. This one is so 
large that it does not make its circuit in one of our 
earth's annual evolutions. It onty intersects the 
orbit of the earth once in thirty-three } T ears. So 
enormous is the extent of that meteoric host that 
our earth rolls by it twice before it passes the point 
of intersection. Thus for two Novembers we should 
have a grand display. 

Whenever the earth meets such a shoal of meteors 
she draws to herself, and never returns, thousands, 
may be millions, of these little bodies. Still the 
enormous stream rolls on its way, apparently not 
lessened. 

If meteors are too small to be seen by use of a 
telescope until they come near our earth, how can 
their path be found out ? 

Although the meteors are invisible, great comets 
are very visible. It has been found that the known 
track of a great comet is identical with that portion 
of the track of a meteoric shoal of which we are as- 
sured, as the Leonids and some other shoals. This 
relationship between comet tracks and meteor paths 
has been observed more than once. This leads not 
only to the discovery of the orbit of the shoal and 



/Ifeeteors anfc Sbootfn^ Stat3 193 

the return to intersect the earth's path, but suggests 
that there is some close and singular connection be- 
tween star showers and comets. 

Thus far w r e have spoken of shooting stars or 
great meteors. We are told that some of these reach 
the earth as meteoric stones. The meteoric stones 
which are mentioned as having fallen to the earth 
are not the same class of bodies as shooting stars. 
Meteoric stones have been known since stones 
began to be studied, but it was long denied that they 
fell from the clouds. " It is impossible. There are 
no stones in the clouds," folks said. 

Within this century the celestial origin of meteor- 
ites has been admitted. They do fall upon our 
earth. Some of them are almost pure iron, and 
these have been found on the earth's surface, far 
from any iron deposits. Many meteorites have been 
seen to fall. The fall is accompanied by a loud, 
rushing noise, and an explosion. When picked up 
soon after their fall they are warm or hot. In shape 
they are rough and irregular, like broken fragments 
from larger bodies. Gold, carbon, helium, and other 
materials are found with the iron in these stones. 

There are many theories about the origin of mete- 
orites. Some fancy that they are cast out by vol- 
canoes upon some other planet ; others think that 
they come from volcanoes upon the earth, in the 
13 



194 BettonomE 

earlier ages of earth-building, and have been whirling 
around in our atmosphere ever since, but have finally 
tumbled back to earth as their motion slowed up. 
All these are but unproven theories. A meteoric 
stone appears to be a very simple affair, but it is a 
something which we know very little about. 

The infinitely great and the infinitely little are 
alike beyond the grasp of human comprehension. 
The problem of the outposts of this wonderful 
universe eludes us ; we can study only those nearer 
parts within telescopic range. So with these very 
small parts of our system, the tiny meteors, small as 
dust, we cannot pick them up with eyes or instru- 
ments ; but as with that part of greatness which lies 
near us, and we can see and reason about, so with 
that part of smallness, these little vagrant bodies 
w T hich become near and visible, we may study them 
and argue from less up to more. As of all other 
bodies of our system except the sun, we say of the 
meteors they are not self-luminous, but neither is 
their brightness reflected as that of the planets ; it is 
brillianc}^ gained by rapid motion, the converting of 
that motion into heat. Our earth moves about thirty- 
two thousand yards a second, and the meteors move 
about thirty-nine thousand yards in a second ; when 
a shower of these meteors meets the earth's atmos- 
phere the combined speed is very great, and the 



flfceteors an& Sbootfna Stars 195 

shock produces a tremendous heat ; the meteor may 
be melted or volatilized at once, or it may be merely 
heated very hot, and go on through our atmosphere, 
increasing its heat. Very likely the greater part of 
the meteors which come within our atmosphere — 
and they are computed to be forty-six billions yearly 
— reach the earth in the form of a fine deposit of 
dust, and are thus slowly adding to its mass. 

Various interesting experiments have been made 
with meteoric stones. Mr. Lockyer found that by 
heating them to luminosity he could obtain by the 
spectroscope evidences of matter such as we find in 
the spectra of nearly all heavenly bodies, and from 
this he concluded that all stars, nebulae, comets, 
are closely related to meteors, and grasping one of 
them we hold part of the matter of which all the 
splendid worlds of space are made. 

A great part of what is said of meteors is entirely, 
and some of it idle, conjecture. For instance, it is said 
that they intercept the sun's heat irregularly, and so 
change our earth temperature, making fitful seasons ; 
that they cause zodiacal light, and also auroras, and 
that they affect the moon in the same way that they 
do the earth ; that they also are the fuel of the sun, 
falling into his blazing fires and re-supplying them 
with combustibles. The absurdity of some of these 
theories has been abundantly proven, and others are 
yet under discussion. 



CHAPTER XX 

THE VAGRANTS OF THE SKY 

"Comets, imparting change of times and states, 
Brandish your crystal tresses in the sky !" 

It seems that shooting stars, meteors and comets 
are pretty closely connected, whether we consider 
their motions or material ; indeed, one or two noted 
astronomers have suggested that these " shoals of 
meteors n are only comets that have gone to pieces ; 
and that at least some comets are " swarms of stones," 
revolving swiftly, kept closely together, whirling 
around the sun, held by his attraction. Chemistry 
shows us that comets and meteoric stones seem to be 
of the same material in different states. 

For three months, in 1858, Donati's comet was 
visible in its vast distance — small, pale, hanging like 
a bit of floating nebulae against the sky, while science 
and newspaper gossip chronicled its every change, 
and it was watched with awe or terror. Comets have 
regular orbits much more elliptical than those which 
the planets follow. This long ellipse brings them 
very near the sun in some places, and very far from 
the sun in other parts of the orbit. The velocity 
196 



Gbe Warrants of tbe Sfes 197 

of the comet is enormous when near the sun, when 
far away it moves slowly. As the comet of 1858 in 
September neared the sun in its path, a vast and 
splendid tail unfolded ; a tail supposed to be three 
millions of miles in length. The nights were dark, 
and this great flaming thing sped across the heavens. 
wrapped in a strange glory. 

Another comet appeared in 1882. Early in the 
morning before the dawn one might watch on our 
Eastern coast, above the waste of the Atlantic, that 
long train of light, that glowing head, rushing sun- 
wards. This comet was so intensely bright that it 
was even seen in the daytime. Three things about 
it made it famous : it was photographed ; the spec- 
troscope analyzed it, and it was found that it had 
sodium, iron, and carbon among its materials ; and 
it finally approached nearer the sun than any comet 
that had been previously observed. 

Comets approach nearer the earth than stars are 
found. Some of them return at short intervals, and 
seem to belong entirely to our system. One or two 
are known to have part of their orbital path beyond 
Xeptune. Other comets appear to us once, among 
our planets ; they seem to come from far-off stellar 
space. They are visitors, coming apparently for the 
first time, and retreating without any distinct promise 
that mankind will ever see them again. 



198 Betronotns 

We know that comets are composed of very thin 
material, of the most delicate gases, for sometimes 
they pass between us and some of the stars ; and 
then the stars can be seen about as clearly through 
the volume of a comet as if the comet were away. 
Even a thin nebulae can be seen through a comet's 
tail. Arcturus showed as bright as ever through 
Donati's great comet. Any gas or air which we 
know anything about in this world would refract or 
bend the rays of a star seen through it, and so make 
it change its apparent place. Comet stuff has no 
such refracting pow T er ; while we speak of it as 
gaseous, we know that it is far less dense than any 
gases that have been dealt with in this world. 

Comet stuff being of such small density we under- 
stand that their weight must be but small indeed in 
proportion to their bulk. Therefore their attractive 
power is very small. If this were not so they would 
be dangerous visitors in our solar system. In their 
onrush toward the planets they might derange the 
planets' motions, even drag them from their orbits. 
Instead of this the planets seem to be uninfluenced 
by these wild intruders. 

There are more comets than planets. " Comets are 
as multitudinous as insects in the forests, or as fishes 
in the sea," says one astronomer. Their orbits are 
very eccentric ; not only that, they zigzag in and out 



Zbc Uaarants of the Sky 199 

about their orbital track, and dash about at all 3orts 

of angles as capriciously as little dogs at play. 

Comets have been named after astronomers who 
have calculated their orbits and predicted their re- 
turn. Thus we have Donati's, Halley's, Encke's, 
Biela's comets, and others. 

Comets have strange and varied shapes. Some are 
curved like swords, or bent into bows. We associate 
tails with comets, but many are tailless, being mere 
burning heads wildly floating about. Some, on the 
other hand, have two or three tails. Cheseaux's 
comet had six tails. 

The tails of comets are always turned from the 
sun, and the nearer the comet is to the sun the 
greater the expansion of the tail. As the comet re- 
cedes from the sun the tail again shrinks. 

The early history of Halley's comet has been 
learned from records kept by the Chinese. This 
comet is to blame for many of the silly superstitions 
about the direful omens of comets, and that they 
appear as presaging human disasters. It happened 
that this comet appeared several times on the eve of 
more or less great events, and was therefore accused 
of foretelling these events. It is very easy to be 
mistaken. 

Halley's comet has been within visible distance of 
the earth twentv-six recorded times. In 840 A. D., 



200 BetronomE 

it frightened Louis LeDebonnaire, King of France, to 
such an extent that he set himself to fasting, pray- 
ing, building churches and convents. Two } r ears 
later he died, and every one was sure that the comet 
had been sent as a harbinger of his death. Surely 
a great messenger for a small errand. 

Back came this same comet the very month that 
William the Conqueror took possession of England. 
In 1455 the Turks and the Crusaders were engaged 
in terrible battles, and the Turks threatened to over- 
run Europe. Again this same comet appeared. The 
Turks claimed that the comet had come to aid them. 
However the Christians won the day, and all the 
church bells were rung for joy of the victory. 

When Halley's comet made later returns people 
had learned that the great sky vagrant had no con- 
nection with human events. 

Newton and other astronomers have predicted that 
eventually the sun w T ould draw into himself all the 
comets, thus renewing his store-house of light and 
heat. One remarkable fact about comets is that 
they have carbon in their composition, and carbon 
is a material usually associated with organic life. It 
is also a notable fuel, and many comets are 
doubtless to end by entering the globe of the sun, 
thus possibly returning to their source " as life to 
the bosom of Braham." 



Gbe Daarante ot tbe Sky 201 

Encke's comet presents many peculiarities, and to 
the mathematical astronomer is, perhaps, the most 
interesting of all the comet tribe. For some reason 
the orbit of Encke's comet is constantly becoming 
smaller and rounder. It has always been among 
" the short period comets," and was the first of these 
noted. Its time has been three years and four 
months. Ordinary observers pay very little attention 
to this especial comet, for it is so faint and small that 
it can only be beheld through a telescope, and then 
is undefined and misty, like a smoke wreath drift- 
ing out and fading upon the air. Now it is seen that 
this pale comet is moving in a spiral, winding con- 
stantly inwards toward the sun. 

It is estimated that in a thousand or fifteen hun- 
dred years Encke's comet will tumble into the great 
central fire about which it is now circulating with 
the infatuation and rashness of a moth about a 
candle. Before that happens some catastrophe may 
overtake and explode or dissipate the entire comet, 
as Biela's comet was supposed to have come to 
wreck; or possibly some new influence may turn it 
about and send it far away, again to reapproach the 
sun in an inward spiral path. 

The best explanation of the curious changes in the 
course of Encke's comet is that it meets and is held 
back by the attraction of a swarm of meteors ; the 



202 Bstronomg 

meeting of such a swarm, and the retardation of the 
comet, would cause the orbit to shrink, and also 
while the period was shortened the speed of the 
comet would accelerate. Encke's comet is supposed 
to be two hundred thousand miles nearer the sun 
than it was at the beginning of this centur) r . 

If comets were not subject to the universal laws of 
gravitation their paths could not be calculated, and 
their return accurately indicated. The path of a 
comet was demonstrated by Newton to be not an 
ordinary ellipse, but a parabola, which is an extreme 
form of ellipse; until his day the erratic orbits of 
comets had never been reduced to geometrical form. 
The moment a path of regular form was discovered, 
then the comet's whereabouts on that path at any 
given time could be calculated. A comet is known 
rather by its path than its appearance, for the form 
of a comet may change. As we have seen, its tail or 
tails expand and contract, and also comets lose their 
tails, the burning matter forming them being dissi- 
pated or reabsorbed into the head. 

At any hour or at any season comets may appear 
in any part of the heavens, and wherever they are, 
wonder and admiration will follow their wayward 
paths. 

These comets fill us with aw f e and an absorbing 
interest; the grandeur of the universe seems con- 



Cbe Warrants of tbe 5ft£ 203 

stantly to grow upon the mind as it strives to follow 
one of these flaming pilgrims along his mighty track ; 
the soul is upborne into the region of higher and 
higher things. 

i ' The stars are forth, the moon upon the tops 
Of the snow-shining mountains— beautiful ! 
I linger yet with nature, for the night 
Hath been to me a more familiar face 
Than that of man ; and in her starry shade 
Of dim and solitary loveliness 
I learned the language of another world." 



THE END 



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